Welcome to the UTT Manuals and Examples Page!
Introduction
UTT(Universal Tracer Tracker) is a tool to track and visualize the trajectory of various materials specified by the user using the calculation result of various flow calculation solvers implemented in iRIC. The target transported substance is not only completely following the flow, but also the substance itself has a cruising ability, a typical example is a fish, by specifying its ability and characteristics to express its movement.
The UTT determines the concentration (density) of the tracer particles at a given location in the fluid and it has the ability to clone or amalgamate itself as needed. This usually allows the tracer to be visualized the image in the detached area where particles cannot easily invade, or in the area where particles have accumulated and become extremely difficult to see.
In addition, UTT can also display weighted particle concentrations that take into account splitting and binding. It is possible to analyze the concentration by a substantial Lagrangian method.
Note that the UTT can extract the turbulence below the grid scale modeled in the solvers by introducing a random walk model. This allows to examine more realistic particle tracking and concentration diffusion fields.
Basically, there are three types of tracers to be tracked in UTT.
Normal tracer (tracks only the position of particles)
Special tracer (also records and displays the position of its trajectory)
Fish tracer (a fish tracer that propels itself)
In addition to these, rod-like shape tracers such as driftwood tracers and can be tracked with their own movement and rotation
Driftwood tracer, NaysDw2 (2D driftwood tracking solver), which is a separate solver from UTT.
The computation of UTT is performed by the following procedure.
Computation of flows with flow calculation solvers (Nays2dh, Nays2dFlood, Nays2d+, etc.)
Saving of flow calculation results (CGNS file)
Starting UTT
Setting tracer input and tracking conditions
Tracer tracking calculation using the above CGNS file.
Visualization of the calculation results
April 26th, 2021 Yasu and Jon
Overview
In this section, we describe the basics of the UTT model.
How to describe the locations of tracers
The positions of the tracers used in the UTT are represented using normalized coordinates in the downstream and transverse directions. For example, when boundary-fitted coordinates are used for rivers, as shown in Figure 1 , Non-dimensional coordinates of \(\xi\) in the downstream direction, and \(\eta\) in the transverse direction show the location of the tracers using values between 0 to 1.
:Non-dimensional description of tracers’ position
Random walk model considering the effect of turbulence
According to Callies (2011), and McDonald and Nelson (2020), the target tracer’s position vector \(\boldsymbol{r}\) is expressed by the following equation
\[\boldsymbol{r}(t+\Delta t) = \boldsymbol{r}(t)+ \boldsymbol{U} \Delta t + \boldsymbol{U}_p \Delta t + \boldsymbol{L}\sqrt{2K\Delta t}\]
Where \(\boldsymbol{U}\) is the velocity vector of the flow, \(\boldsymbol{U}_p\) is velocity vector of a tracer (the tracer’s own propulsive velocity vector), \(\boldsymbol{L}\) is a Gaussian vector whose values are such that it has mean 0 and standard deviation 1, \(\Delta t\) is the computation time step, and \(K\) is the turbulent diffusion coefficient.
Applying the Box-Muller transformation (Box and Muller, 1958) for \(\boldsymbol{L}\) , the following equations are obtained for the two-dimensional case.
where \(U_1\) and \(U_2\) are mutually independent 0 to 1 normal random numbers. This is the so-called Random Walk model, When these are applied for tracer tracking. \(K\) can be given as a linear function of \(\nu_t\) as,
In the UTT model, \(a\) and \(b\) in the above equation are given as parameters. As for \(\nu_t\) , it is automatically loaded from the result of the flow calculation.
Tracer cloning
The tracer supplied from upstream is transported downstream by the flow, but depending on the flow conditions, the tracers may not be got into areas particularly, in the place where the flow is stagnant, the separation zone, and the one of the paths where the flow is divided, etc, even if a large amount of tracer is supplied from upstream, it may not easily to reach the target region. In general, there is an upper limit to the number of feeds from the upstream, and it is not infinite, so some ingenuity is required. In the UTT, a new tracer can be added to a cell with a small number of tracers (or no tracers), to control the tracer concentration while tracking the flow even in areas where there is not enough tracer. For example,
When the number of tracers in a cell reaches one, split it into two
But the weight is set to 1/2, and it is stored
Cloning can be repeated as many times as necessary, but it can be terminated at a given generation.
Optionally, a single tracer can be generated for cells with zero tracers.
In this case the tracer The weights are assumed to be zero, but visualization is possible, so it is effective as a tracer for flow visualization.
Figure 2 shows the schematics of the tracer division.
: Division of the tracer (image of cloning)
When defined as the first tracer submitted is the first generation, the one generated by the first split is the second generation, and the next one is the third generation… The wight is 1/2 at the second generation, the weight is 1/2 in the third generation, and the weight is 1/4 in the fourth generation. In the \(n\) generation, considering it is experienced \(2^{n-1}\) times cloning, it’s weight becomes \(W={1}/{2^{n-1}\) . Using this, we can count the total number of weighted tracers in each cell to obtain concentration can be calculated. Thus, for example, in the 10th generation when \(n=10\) , weight is \(W=\cfrac{1}{2^9}=0.000195\), and in the 20th generations when \(n=20\), the weight becomes \(W=\cfrac{1}{2^{19}}=0.00000195\) .
Calculation results of two-dimensional flows used in UTT
Since the UTT tracks tracers in a two-dimensional “flow” in a Lagrangian manner, the results of the “flow” calculation have to be prepared in advance( Figure 3 ). By default, the UTT read the flow information stored in the CGNS files with 2-dimensional structured grid format. At present, flow solvers which satisfy this condition in iRIC (as of April 1, 2021), are Nays2dH, Nays2dFlood, Nays2d+, and FastMech. For more information about the flow calculation models available in iRIC, please visit the iRIC website (https://i-ric.org/) for more details.
: Calculation Procedure by UTT
The CGNS file that contains the calculation results of the flow used in UTT is Specify from [Calculation conditions], [Settings], and [CGNS file to load flow calculation results] of the bar. (Figure 4)
: Specify the CGNS file which contains the calculation result of the flow
Computational grids used in UTT
In most cases, the computational grid is imported from the GNS files which contains the computational flow results. As shown in Figure 5 , from the “Object Browser” in the “Pre-Preprocessing Window”, Right-click [Grid(No data)], select [Import], and select a CGNS file which contains the grid information as Figure 6 . In most cases in iRIC, the file name is [Case1.cgn].
: Importing computational grid.
: Select a CGNS file
When you try to read the grid data from CGNS file produced by other than UTT, Figure 7 is displayed. This means that the current project(UTT project) is different from the flow calculation project. This is a warning that you are trying to import grids from a wrong project, but you can just click “OK”, and the grid information is imported and the result is displayed as Figure 8 .
: Warning message
: Grid import completed
After this, the following procedure is used to calculate the tracer and display the result by UTT. Examples are given in the next section.
Set computational condition
Calculation execution
Visualization of the solution
Examples
In this section, we show an actual example of calculation by UTT.
[Example 1] Tracer transport in a straight channel
Flow calculation by Nays2DH
Select a solver
In the [iRIC start page] , select [Create New Project], and when the [Select Solver] screen appears, choose [Nays2DH iRIC 3.x 1.0 64bit] and click [OK] button.
: Select Solver
A windows with “Untitled - iRIC 3.x.xxxx [Nays2DH iRIC3X 1.0 64bit]” appears as Figure 10.
: Untitled
Grid Generation
From the main menu of the screen, Figure 10, choose [Grid]->[Select Algorithm to Create Grid] as Figure 11.
: Select Algorithm to Create Grid
In the [Select Grid Creating Algorithm] window, select [Simple Straight and Meandering Channel Creator] and click [OK] (Figure 12).
: Select Grid Creating Algorithm
In the window of Figure 13 , click “Channel Shape” and set [Select Channel Shape of the Main Part] as [straight channel], and other values as shown in Figure 13, then click [Create Grid].
:Setting Channel Shape
When the confirmation window appears as Figure 14, click [Yes] to generate the grid, then the computational grid is generated as Figure 15 .
:Confirmation of mapping
:Grid Generation Compete
Setting of calculation conditions for flow by Nays2DH
The next step is to set the calculation conditions. From the menu bar, select [Calculation Conditions]->[Settings], then the [Calculation condition setting window] as Figure 16 appears.
:Calculation Condition Window
As Figure 17, in the [Group] of the [Boundary Condition], click [Edit] at the [Time series of discharge at upstream and water level at downstream]. Then the [Time series of discharge at upstream and water level at downstream] appears as Figure 18 .
: Boundary Condition
: Time series of discharge at upstream settings
In Figure 18, input [Time] and [Discharge] values, and click [OK] when you finish, and close this window.
:Time parameters
Select [Time] and set parameters as Figure 19 and click [Save and Close].
Flow calculation run by Nays2DH
:Window when the solver is running
From the main menu, when you select [Simulation]->[Run], you will get the message like “We recommend you to save the project before running solver. Do you want to save?” Select [Yes] and save the project with an appropriate name. At this time, do not save the project as an ipro file, but save it as a project. A window as Figure 20 is shown during the computation, and Figure 21 appears when the computation is finished. Then press [OK], and the computation is completed.
:Computation completed
Important Whenever you finished the computation, select [File]->[Save] from the menu bar to save the results as Figure 22 . This result is important for later analysis by UTT.
:Saving computational results
Visualization of the calculated results
After the calculation, select [Calculation Result] -> [Open New 2D Post-processing Window] to open the visualization window.
: 2D Post-processing Window
Velocity Vectors
In the [Object Browser], put check marks in the boxes by [Arrow] and [Velocity], click Focus on [Arrow] and click the right mouse button [Properties]. Vector setting” window as Figure 24 appears. Set the values in the red line and click [OK]. Figure 25 is the depth-averaged velocity vector. Here, the velocity distribution is uniform under the constant flow condition.
: Vector Settings
: Depth averaged velocity vectors
Display Particle Movement
Uncheck “Vectors” in the Object Browser, and put check marks in “Particles” and “Velocity” ( Figure 26 )
: Particles(1)
Right click [Particle] and select [Properties] as Figure 27 .
: Particles(2)
Set parameters for particle injection as shown in red box in Figure 28 .
: Set particle parameters
As shown in Figure 29 , set time bar back to zero, and select [Animation]->[Start/Stop Animation] rom the main menu bar. Then the particle animation starts.
: Start Particle Animation
: Particle animation by NAys2DH
As can be seen in Figure 30, since the sub-grid scale turbulence is not included in the output velocity from the solver. It only shows very simple steady and uniform movement.
Tracer Tracking by UTT
Starting UTT
From the iRIC startup screen, select [New Project], and in the solver selection screen appears. Select “UTT” and click “OK” ( Figure 31 ).
: Selecting UTT and Starting
A window with [Untitled -iRIC 3.0.xxxx] [UTT] appears, and the UTT session is started. (Figure 32 )
: Opening UTT
At this stage, the [Grid] in the [Object Browser] shows [No data] as shown in Figure 32 , we will first import the grid data created in Grid Generation session.
: Grid data import
Right click [Grid(No Data)] and select [Import] as (Figure 33 ).
: Select CGNS file contains grid data
As shown in Figure 34, select [Case1.cgn] which contains the grid data used in the previous section of [Computational Results of NAys2DH], and click [Open].
: Warning Message
A warning message is coming out as Figure 35 , Just click [Yes] without worry, and the grid import is completed as Figure 36 .
: Grid import completed
Single Tracer Tracking(Without Turbulent Diffusivity)
Condition Settings
Choose [Calculation Condition]->[Setting] as Figure 37
: Calculation Condition Settings(0)
As shown in Figure 38 set filename at [Basic Settings]-> [Flow information file name] as the CGNS file to read the calculation result of the flow field. Here, the CGNS file produced by the Nays2DH computation. ( Flow calculation run by Nays2DH ).
: Calculation Condition Settings(1)
The rest of the [Basic Settings] are set as Figure 39 . Note that the tracers used are only [Normal Tracers]. The tracers used here are [Normal Tracers] only, but no [Special Tracers] are used.
: Calculation Condition Settings(2)
[Normal Tracers Supplying Conditions]are set, using the parameters described in How to describe the locations of tracers, as Figure 40.
: Calculation Condition Settings(3)
Set [Diffusion Condition]->[Diffusivity Correction]->[No], and click [Save and CLose]
: Calculation Condition Settings(4)
Launch UTT
From the main menu bar, select [Simulation]->[Run], then you are asked [Do you want to save?] as Figure 42. When you click [Yes] and save project, the computation starts as Figure 43.
: Do you want to save?
: Launch UTT
When the computation finishes, Figure 44 appears, and click [OK] for confirmation.
: Computation finished
Visualization of Computational Results
From the main menu, select [Calculation Result]->[Open ne 2D Post-processing Window], then [2D Post Processing Window] appears as Figure 45.
: 2D Post Processing Window
From the main menu, select [Animation]->[Start/Stop] as Figure 46, animation starts ( Figure 47 ).
: Visualization of computational results
: Tracer movement(No diffusivity)
It is obviously very simple because it doesn’t including any turbulent effect (Figure 47).
Single Tracer Tracking(With Turbulent Diffusivity)
Setting Computational Condition
Change the calculation conditions to take into account for the effect of turbulent diffusion. From the main menu, select [Calculation Conditions] → [Setting], and show the Figure 48. Set [Diffusion Condition]->[Diffusivity Correction]->[Yes], set the parameter [A Value] to [1], and then click “Save and Close”.
: Calculation Condition (Diffusion Condition)
Launch UTT and the Results Visualization
Computation can be conducted through the same procedure as previous example, the animation becomes as Figure 49.
: Tracer Movement(With Turbulent Diffusivity A=1)
When the value of A is set as [10], the results become as Figure 50, the effect of the turbulent becomes stronger.
: Tracer Movement(With Turbulent Diffusivity A=10)
[Example 2] Suspended Material Transport in a Simple Bed Flume
In this section, we perform the following computations using a simple curved flume with straight inlet out let parts. The Cross section of the flume is composed with a compound channel in which both the low water channel and the flood plane with moveable bed. Then flood plane is located only left side of the low water channel. The experiment was carried out by CTI Engineering Co. Ltd. on behalf of Civil Engineering Research Institute of Cold Region . A movie taken from a drone during the experiment is shown in Figure 51, and the experimental condition and plane and cross sectional view pictures are shown in Figure 52.
: Experimental Video
: Flume Shape
The computational exercises in this section is conducted as the following procedure.
Flow and bed deformation by Nays2DH until the bed reaches an equilibrium state
Quasi 3-dimensional flow field by Nays2d+
Tracer tracking by UTT. Check the effect of turbulent diffusivity by changing parameter
Calculation of Flow and bed deformation by Nasy2DH
Select a Solver
From the iRIC startup screen, click [Create New Project], and select [Nays2dH iRIC3x 1.0 64bit] in the Figure 53.
: Solver Selection
A window titled as「Untitled- iRIC 3.x.xxxx [Nays2DH iRIC3X 1.0 64bit]」appears.
: Launch Nays2DH
Grid Creation
Select from the main menu [Grid]->[Select Algorithm]. Then a window appears as Figure 55, select [2d arc grid generator (Compound Channel)] and click [OK].
: Select Algorithm to Create Computational Grid
In the [Groups] of the [Grid Creation] window, set parameters of, [Channel shape], [Cross section], [Additional Channel] and [Roughness and fixed/moveable bed] as, Figure 56 , Figure 57 , Figure 58 , and Figure 59 , respectively.
: Grid Creating Condition(1)
: Grid Creating Condition(2)
: Grid Creating Condition(3)
: Grid creating Condition(4)
When you finished all the settings of the grid creating condition, click [Create Grid] in the above grid creating condition windows, e.g. Figure 59. After clicking [Create Grid] button, you will be asked [Do you want to map?], then answer [Yes], and the computational grid is created. ( Figure 60 )
: Confirmation of mapping.
Put check marks in [Grid], [Cell Attributes] and [Fixed or Moveable bed] in the object browser, Figure 61 appears with the fixed bed part in red and the moveable bed part shown in blue.
: Grid Shape with Fixed and Moveable bed Colored
The red part of the fixed bed along the boundary between the low water channel and the flood plane is assumed to be a revetment, in this grid creating tool, however, since the revetment in the actual experiment is only the bend part plus short length of upstream and downstream. So, as shown in Figure 62, focus [Fixed or Moveable bed], and right-click on a straight section of the revetment part (in this case, the red section upstream of grid number 87) and change the attribute to [Moveable bed], and press [OK].
: Change attribute from fixed bed to moveable bed
Since the downstream end is the fixed bed, set the attribute of the downstream end cells into [Fixed Bed], by expanding and rotating, as demonstrated in Figure 63.
: Change downstream end cell attribute to fixed bed
Setting Computational Condition
Show the [Calculation Condition] window by selecting [Calculation Condition]->[Setting], and in the [Group] of [Solver Type], [Boundary Condition], [Time] and [Bed Material] , set the parameters, as Figure 64 , Figure 65 , Figure 66 , and Figure 67, respectively.
: Calculation Condition(Solver TYpe)
: Calculation Condition(Boundary Condition)
: Calculation Condition(Tme)
: Calculation Condition(Bed Material)
In addition, in the [Boundary Condition] setting of Figure 65, press [Edit] of [Time series of discharge at upstream end ……], and set [Time] and [Discharge] hydrograph data in the [Time series of discharge at upstream end ……] window as Figure 68, and press [OK].
: Setting Discharge Hydrograph
When you finished the settings of all the computational condition parameters, press [Save and Close] in the [Calculation Condition] window.
Run Nays2DH
Before executing the Nays2DH, select [File]->[Save as Project] and save the project. Here we save the project as a name of [Nays2DH_flow_bed] (Figure 69)
: Save Project
From the main menu, select [Simulation]->[Run], then a window asking [Do you want to save?] appears as Figure 70. Then press [Yes], save as a project, and the computation starts running as Figure 71.
: 「Do you want to save?」
: 「Nays2dH is running」
When the computation finished, save the results by selecting [Calculation Result]->[Save], from the main menu.
Display the Calculation Results
Open a [Post Processing Window] by selecting [Calculation Result]->[Open new 2D Post-Processing Window] as Figure 72.
: Open Post Processing Window
In the object browser of the [Post Processing Window], put check marks in [iRICZone], [Scalar(node)] and [ElevationChange(m)], right click [ElevationChange(m)] to show [Property] and press it, open [Scalar Settings], and set parameters as Figure 73.
: 「Scalar Setting」
In the object browser, put check marks in [Arrow] and [Velocity(m)], right click [Arrow], show [Property] and press it, open [Arrow Setting Window] as Figure 74, and set parameters as marked with red squares in the Figure 74.
: [Arrow Settings]
Put the [Time Scale Bar] back to zero, select [Animation]->[Srart/Stop] to start animation as Figure 75.
: [Launch Animation]
As shown in Figure 76, it is shown that the bed elevation change reached an equilibrium.
: Animation of velocity vectors and bed elevation changes
Export the Computational Results
In order to use the calculated bed elevation as an boundary conditions for the quasi-3D flow calculation by Nays2d+ in the next section, we export the calculated results to a text file. As shown in Figure 77, select [File]->[Export]->[Calculation Result].
: Exporting Computational Results(1)
When the [Export Calculation Result] setting window (Figure 78) is appeared, choose [Format] as [Topography Files(*.tpo)].
: Exporting Computational Results(2)
The output folder can be any name, and uncheck the checkbox at [All timesteps], and set [Start] and [End] as 7,200. Then click [OK] to complete the export of the calculation Results Figure 79.
: Exporting Computational Results(3)
The exported calculation results are stored in the specified folder. As shown in Figure 80, many files contain different values as water depth, velocity, sediment transport rate, riverbed elevations, and so on, however, since only the riverbed elevation is used for the flow calculations in the next section, all files except [Result_1_Elevation(m).tpo] can be deleted.
: Exporting Computational Results(4)
Quasi-3D Flow Calculation by Nays2d+
Selecting a Solver
From the iRIC startup screen, click [Create New Project], and select [Nays2d+] in the Figure 81, and press [OK].
: Solver selection of Nays2d+
Importing Computational Grid, Channel Bed Elevation and Mapping
Importing Grid
From the main menu, select [Import]->[Grid], and choose [Case1.cgn] in the folder of [Nays2DH_floe_bed] which was created in the previous section. While importing, a warning as Figure 82 is coming out, press [Yes], and complete importing grid (Figure 83).
: [Warning]
: [Grid import complete]
Import Bed Elevation
From the main menu, select [Import]->[Geographic Data]->[Elevation](Figure 84).
: Import Elevation
In the import file selection window, Figure 85, assign the file [Results_1_Elevation(m).tpo], which was exported from Nays2dH calculated results in the previous section.
: Select bed elevation file to import
Figure 86 appears, but if there is no particular need to thin out the data, you can leave it as it is, and press [OK] to complete the import the [Bed Elevation] (Figure 87).
: Import Bed Elevation (Setting Thinning)
: Bed Elevation Data Import Completed
Execute Mapping
The imported bed elevation data is mapped onto the imported computational grid. Select [Grid]->[Attribute Mapping]->[Execute] as Figure 88.
: 「Execute Mapping」
As Figure 89, you will be asked which [Geographic Data] to be mapped. Put check mark in the box of [Elevation(m)], and press [OK].
: Selection of the Mapping Item
When the mapping is completed, press [OK] as Figure 90.
: Mapping Completed
Setting Calculation Condition for Nays2d＋
In the window of [Calculation Condition] which appears when you select [Calculation Condition]->[Setting], set parameters in the [Groups] of [Discharge and downstream water surface elevation], [Time and bed erosion parameters], [Boundary Condition], [Other computational parameters] and [3D Velocity Profile] as, Figure 91, Figure 92, Figure 93, Figure 94, and Figure 95, respectively.
: Discharge and downstream water surface elevation
: Time and bed erosion parameters
: Boundary Condition
: Other computational parameters
: 3D Velocity Profile
In addition, while in the settings of the [Discharge and downstream water surface elevation], Figure 91, press [Edit] and set discharge data in in the [Time series of discharge and downstream stare] setting window as Figure 96.
: Setting the time series of discharge Data
When you finish setting all the calculation condition, press [Save and Close] in the [Calculation Condition] window.
Execute Nays2d+
We will skip the explanation of how to executing Nays2d+ because it is exactly same as other solvers. However, it is recommended that you save the project before running the calculation. In this case, we save the file to a project named [Nays2d+Flow].
: Save project(Nays2d+Flow)
The results are saved in a CGNS file named [Case1.cgn], which will be used for the tracer tracking computation of UTT as input data. Be sure to save the result using [Calculation Result]->[Save] even when the calculation is finished. (Figure 98).
: Save the Results of the Computation (Don’t Forget!)
Tracer Tracking by UTT
Select a Solver
From the iRIC startup screen, select [New Project], and in the solver selection screen appears. Select “UTT” and click “OK” (Figure 99).
: Select and Launch UTT
Import Grid
Right click [Grid(No Data)] and select [Import] as Figure 100.
: [Import Grid(1)]
From the [Select Import File] window as Figure 101, choose [Case1.cgn] in the folder [Nays2d+Flow] which is produced by the [Nays2d+] calculation in the previous section.
: [Import Grid(2)]
Press [Yes] button when warning message is coming out as Figure 102, and the grid import is completed as Figure 103.
: [Warning Message]
: [Grid Import Completed]
Tracer Tracking Simulation by UTT
Setting Simulation Condition
From the main menu bar, when you select [Calculation condition]->[Setting]. [Calculation Condition] window appears, and in this window, set parameters in the [Groups] of [Basic Settings], [Normal Tracers Supplying Condition] and [Diffusion Condition], as Figure 104, Figure 105, and Figure 106, respectively. In this section, we first perform tracer tracking without considering the effect of sub-grid turbulence.
: Basic Settings
: Normal Tracers Supplying Condition
: Diffusion Condition
In addition.Figure 100 The [CGNS file to read the flow calculation results] in the [CGNS file to read the flow calculation results] is the same as the one in the previous section [Flow calculation with Nays2d+]. Select [Case1.cgn] in the [Nays2d+Flow] project folder where you saved the results of ( Figure 103)
In addition, the [Flow information input file] in Figure 104, is the same file with the [Case1.cgn] which was produced by the flow simulation of [Nays2d+] in the previous section (Figure 107).
: Assign CGNS file to read flow simulation results
Run UTT
From the main menu, select [Simulation]]->[Run], then you will be asked to save project as usual, save project as recommended. ( Figure 108).
: Saving UTT Project(1)
In the Figure 109, either [Save as file (*.ipro)] or [Save as Project] will do, but in this example, the file is saved as [UTT1.ipro].
: Saving UTT Project(2)
When the computation starts, Figure 110 appears, and when the computation finishes, Figure 111 appears. Press [OK] to finish computation.
: Execution of UTT(1)
: Execution of UTT(2)
Showing the Results of UTT
From the main menu, select [Calculation Result]->[Open new 2D Post Processing Window], and the calculation results are shown (Figure 112)
: [2D Post Processing Window]
Since the orientation of the Figure 112 is the opposite to the experimental image shown at the beginning of this chapter Figure 51, press the 90° rotation mark twice to rotate 180° (Figure 113).
: 2D Post Processing Window 180° rotate
Since the [Time] display is so small that it’s hard to see, select [Time]->[Properties] in the object browser (Figure 114), display [Time Setting] and set the font size appropriately large (Figure 115).
: Time Setting(1)
: Time Setting(2)
As shown in Figure 116, put time bar back to 0, and from the main menu, select [Animation]->[Start/Stop], then the animation starts( Figure 117).
: Starting Animation
: Tracer Animation (Turbulent Diffusivity A=0)
There is almost no diffusion and the tracers are just flowing straightly.
Comparison of the Turbulent Diffusivity
Select [Calculation Condition]->[Setting] and open [Calculation Condition] window. As shown in Figure 118, set in the [Group]->[Diffusion Condition], [Diffusivity Correction]->[Yes] and set the value [A=1] of the [Diffusivity Parameter]
: Random Walk Parameter Setting (A=1)
: Animation of the Tracer Motion (A=1)
In the same manner, if we do the simulation with [A=5], [A=10] and [A=50], the results becomes as Figure 120, Figure 121 and Figure 122.
: Animation of the Tracer Motion (A=5)
: Animation of the Tracer Motion (A=10)
: Animation of the Tracer Motion (A=50)
When we compared with the experimental results of the Figure 51, it seem that the case with A=10, Figure 121, is the closest to the experiment.
Cloning of the Tracers
In the main menu, select [Calculation Condition]->[Setting] to show [Calculation Condition]. In the [Calculation Condition] window, select [Tracer Cloning and Amalgamation], set parameters as Figure 123. Select [Diffusion Condition] and set [A=1] and press[Save and Close] as Figure 124. Then execute the UTT solver by choosing [Simulation]->[Run], and show the results (Figure 125).
: Setting the Tracer Cloning(1)
: Setting the Tracer Cloning(2)
: Animation of Tracer Cloning (Maximum Generation 20, A=10)
The spread range of the tracers in Figure 51 is close to the diffusion range of the green dye in the experimental movie. The number of tracers appears to be enormous, but if you put check marks in [Particles]->[Scalars]->[Generations] in the object browser, generations of the tracers are displayed as Figure 126.
: Color-coded View of the Clone Generations
When this is animated, it becomes as Figure 127.
: Tracers Clone Animation(Maximum 20 Generations, A=10, Color-coded View)
As described in Overview , the substantial weight in the 10th generation is W=0.00195, and in the 20th generation is W=0.00000195. Therefore, Figure 126, the concentrations of the tracers of green, yellow, red, etc. are logarithmically lower than that of the central blue tracers. To see the real concentration, the substantial concentration in each cell is visualized by the following procedure.
Uncheck the check box at [Scalar] in the object browser (Figure 128).
: Uncheck the check box by [Scalar]
2. Put check mark at [Scalar(Cell Center)] and [Weighted numbers of tracers] in the Object Browser (Figure 129).
: Put check mark at [Weighted numbers of tracers]
Right click [Weighted numbers of tracers] and press [Property]
: [Weighted numbers of tracers]->[Property]
4. In the [Scalar Setting] window, uncheck mart at [Auto], set [Max=0.1] and [Min61e-08], remove the check mark at [Fill Lower Area], set [Color map] as [Manual], and press [Setting].
: Scalar Settings
5. In the [Custom Color Map] window, set [Type] [3 Colors], [Maximum Value] as [Dark Green], [Medium Value] as [Light Green] and [1e-06], [Minimum Value] as [White] and press [OK].
: Custom Color Settings
When the window got back to the [Scalar Settings], press [OK] to finish.
: Scalar Setting (finished)
In the [Post processing (2D)] window, Figure 134, put time bar back to zero, select [Animation]->[Start/Stop], and start animation as Figure 135.
: Starting Animation
: Animation of the tracer concentration considering the weight
The diffusion situation is similar to that of the green dye in the experimental movie of Figure 51.
Flow Visualization using Tracer Cloning
Flow visualization using tracer cloning is shown in this section. In the main menu, click [Calculation Condition], and set parameters in the [Group] of [Normal Tracers Supplying Condition] and [Tracer Cloning and Amalgamation] as Figure 136 and Figure 137, respectively, and press [Save and CLose].
: Calculation Condition Setting(1)
: Calculation Condition Setting(2)
Then after running the UTT solver. in the [Object Browser], remove check mark from [Weighted numbers of tracers], put check marks in boxes at [Particles], [Scalar] and remove the check mark form the [Generation].
From the main menu, select [Animation]->[Srat/Stop], and the animation with evenly distributed tracers in the whole channel is visualized.
: Flow Visualization with Virtual tracers
Swimming Fish Simulation
Set the following parameters in the [Computation of Fish Motion] in the [Calculation Condition] window menu followed by selecting [Calculation Condition]->[Setting] in the main menu.
: Setting Condition or Fish(1)
: Setting Condition for Fish(2)
: Setting Condition of Fish(3)
After setting these parameters, run the solver by [Simulation]->[Run]. Once close the existing [2D Post-processing 2D window], open a new [2D Post-processing 2D window], put check mark on [Polygon]->[Fish]->[Type] as Figure 142, and select [Animation]->[Start/Stop]. Then Figure 143 is played.
: Choosing Fish Animation
: Swimming Fish Animation
Driftwood Tracking by NaysDW2 and Visualization
In this section, driftwood tracking simulation by NaysDW2 (Nays Driftwood 3D) is shown.
Select a Solver
From the iRIC startup screen, click [Create New Project], and select [NaysDw2(Simple 2D Driftwood Tracker)] as shown in Figure 144, and press [OK].
: Selecting [NaysDw2] (Simple 2D Driftwood Tracker)
Import Computational Grid
As shown in Figure 145, from the [Object Browser], right click [Grid(No data)], and press [Import]
: [Import Grid(1)]
When the file selection window appears, select [Case1.cgn] in the [Nays2d+Flow] folder in which the computational results of the [Nays2d+] stored. (Figure 146)
: [Import Grid(2)]
Neglect the waring message as Figure 102, press [Yes], and the grid importing is completed (Figure 148).
: [Warning Message]
: [Grid Import complete]
Setting Condition
From the main menu, select [Calculation Condition]->[Setting],and set the calculation condition as follows.
In the [Calculation Condition] window, press file selection bar as Figure 149.
: Select CGNS File to Read(1)
In the [Select File] window, Figure 150, select [Case1.cgn] which contains the calculation results of the [Nays2d+] in the previous section.
: Select CGNS File
Set other parameters in [Basic Setting] as Figure 151.
: Other settings in [Basic Setting]
Set parameters in [Driftwood Feeding Condition] as Figure 152.
: [Driftwood Feeding Condition]
Set [Flow and driftwood condition] parameters as Figure 153, and press [Save and Close].
: [Flow and Driftwood Condition]
Run Driftwood Simulation
From the main menu, select [Simulation]->[Run] as Figure 154.
: [Simulation]->[Run]
When you are asked [Do you want to save?] as Figure 155, press [Yes] and save the project.
: [Do you want to save ?]
As Figure 156, when you are asked [How to save the project], in this example, select [Save as project], and press [OK].
: [How to save project]
As Figure 157, choose an empty folder to save project, and press [Select Folder].
: Saving Project
When the calculation starts, Figure 158 is displayed, and Figure 159 is appear when the calculation ends. Then click [OK] to finish calculation.
: Solver Running
: Calculation finished
Visualization of driftwood motion
From the main menu, select [Calculation Result]->[Open New 2D Post-processing Window] as Figure 160.
: Open New 2D Post-processing Window
In the [Object Browser] of Figure 161, put check marks in the boxes at [iRICZone], [Scalar(node)] and [res_Velocity(magnitude)], right click [res_Velocity(magnitude)] and choose [Property].
: Scalar Setting(1)
Set the parameters for [Scalar Settings] as Figure 162, and press [OK].
: Scalar Setting(2)
Press [Rotate 90° ] button twice to rotate the object 180° as Figure 163.
: 180° Rotation
Set the time bar back to zero, and select [Animation]->[Start/Stop] from the main menu bar as Figure 164, and start animation as Figure 165
: Start Animation
: Driftwood Tracking Animation
[Example 3] Tracer Tracking Simulation in Real River
In this section, we perform s simulation of tracking floats for the discharge measurements in a real river. Floats are injected from a bridge and velocities are calculated by measuring the flow time between two sections ste up with 100m interval in which the upper section is located 130m downstream of the bridge. Using a discharge of 384m \(^3\)/s, flow calculation is conducted using Nays2d+, and the paths of the floats are simulated by UTT.
Flow Calculation by Nays2d+
Selection of Solver
From the start window of the iRIC, launch [Nays2d+] as Figure 166.
: Solver Selection
Import Geometric Data and Making Computational Grid
Importing River Bed Elevation Data
From the main menu, select [Import]->[Geographic Data]->[Bed Elevation(m)] as Figure 167, and read “tikei.tpo (Point Claud Data)” as shown in Figure 168.
: Import River Bed Data File
: Selecting a tpo file
While reading the data, you need to set filtering value as Figure 169. In this example, choose [1] just for without filtering.
: Input Filtering Value
The geometric data (ground elevation data) is shown as Figure 170.
: Geometric Data
Setup Background image
From the main menu, select [File]->[Property], and press [Edit] button at [Coordinate System:] information as Figure 171.
: Project Property
in the [Select Coordinate System] window, type “Japan” at [Search:] box, and select [EPSG ….. Japan …. IV] from the list below the [Search:] box, and press [OK] as Figure 172. Then close the [Project Property] window by pressing [Close].
: Select Coordinate System
In the [Object Browser], put check marks at [Background Images (Internet)] ->[GSI (Ortho images)(Japan only)] as Figure 173.
:Select Background Image
Grid Creation
From the main menu, select [Grid]->[Select Algorithm to Create Grid], and select [Create grid from polygonal line and width] in the next window (Figure 174)
: Select Grid Creating Algorithm
Assign channel center points from the upstream side to down stream side as Figure 175. 上流側から下流へ向けて中心位置を選択する.
: Assign Center Points
In the [Grid Creation] window, Figure 176, input values as Ni=200, Nj=60 and W=120, then the grid size becomes about 3.2mx2m as Figure 177.
: Grid Creation
: Created Grid Shape
Setup for Bridge Piers
From the [Object Browser] in the left side of the window, hide the [Point Cloud Data 1] by removing the check mark. Right click [Obstacles], select [Add]->[Polygons], and make polygons by clicking the outer edge of the piers, and assign them as [Obstacle] (Figure 178) Surround all the cells in one polygon and assign it as [Normal Cell]. Note that the [Normal Cell] polygon has to be located at lower layer than the [Obstacle] polygons (Figure 179).
:Obstacle Cells for Bridge Piers
:Normal Cells for All the Area
Set Manning’s Roughness Coefficient
[マニングの粗度係数]よりポリゴンから全格子囲みn=0.030を入力する.
In the [Object Browser] under the group of [Geographic Data], right click [Manning’s roughness coefficient] and select [Add]->[Polygons], and make a polygon covering all the grid domain, and input n=0.030 (Figure 180).
:Set Manning’s Roughness Coefficient
Attributes Mapping
From the main menu, select [Grid]->[Attributes Mapping]->[Execute] (Figure 181).
:Select Attributes Mapping
Put check marks at [Elevation(m)], [Obstacle] and [Maninng’s roughness coefficient] in the [Attribute Mapping] window as Figure 182, and press [OK] to execute mapping.
:Choose Mapping Items and Execute Mapping
Set Calculation Condition
From the main menu, select [calculation Condition]->[Setting], and input parameters in the [Calculation Condition] window as the following figures of Figure 183, Figure 184, Figure 185, Figure 186, Figure 187 and Figure 188. When you finished to input parameters, press [Save and Close].
:Discharge and downstream water surface elevation settings
:Time series of discharge and downstream stage
:Time and bed erosion parameters
:Boundary Condition
:Other computational condition
:3D Velocity Profile
Execute a Solver
Save the project with some name, and run the solver by [Simulation]->[Run]. When the simulation finished, save the results and close the project.
Tracking Virtual Tracers by UTT
Select a Solver
In the [Select Solver] window, which appears when you select [Create New Project] in the startup window of the iRIC, select [UTT] and press [OK] as Figure 189.
:Select UTT Solve
Import Grid Data
Right click [Grid(No Data)] in the [Object Browser] and select [Import] as Figure 190.
:Select UTT
Choose [Case1.cgn] which contains the calculation results of [Nays2d+] saved in the previous section (Figure 191)
: Select a File to Import
Confirmation of Geographic Data
Set coordinate system by selecting [File]->[Property] from the main menu as Figure 192.
:Select Property
In the [Project Property] window, press [Edit] located at the [Coordinate System:] lin (Figure 193)
:Project Property
Type “Japan” in the box next to [Search:], select a line with [ EPSG:…Japan….CS VI], and press [OK] as Figure 194.
:Select Coordinate System
Select [Background Images(Internet)]->[GSI(Ortho images)(Japan only)] from the Object Browser as Figure 195.
:Background Image
Tracer Tracking by UTT
Calculation Condition
From the main menu, select [Calculation Condition]->[Setting], and set the [Calculation Condition] as Figure 196, Figure 197, Figure 198 and Figure 199. In which the CGNS file to read in the Figure 197 is usually the same file imported for calculation grid in Figure 191.
:[Basic Settings]
:Set the CGNS file to read the flow field information
:Set special tracer information for path tracking
:Diffusion Condition
Execute Calculation
From the main menu, save thr project by selecting [File]->[Save Project as], and execute UTT by selecting [Simulation]->[Run].
Visualization of the Calculation Results
From the main menu, select [Calculation Result]->[Open new 2D Post-Processing Window]. Put check marks in [Background Images(Internet)] and [GSI(Ortho Images)(Japan only)] in the Object Browser, as Figure 200.
:Show Background Image
Right click the [Trajectory] at the [Polygon] in the Object Browser, and select [Property] as Figure 201.
:Property of the Polygon
In the [Polygon Setting] window, set [Line Width] as [3] as Figure 202.
:Polygon Setting
From the Object Browser, put check marks at [Scalar(node)] and [Velocity] and right click [Velocity] and press [Property]. In the [Scalar Setting] window, as shown Figure 203, uncheck [Automatic], set [Max:] and [Min:] vales, and uncheck [Fill lower area].
:Scalar Setting
After above settings the calculation results of the tracers injected from the Bridge can be visualized as follows.
:Tracer Tracking Paths
: Tracer Tracking Animation
References