Kratos Multi-Physics 3D Fluid Analysis Tutorial. Pooyan Dadvand Jordi Cotela Kratos Team

Transcription

1 Kratos Multi-Physics 3D Fluid Analysis Tutorial Pooyan Dadvand Jordi Cotela Kratos Team

2 Kratos 3D Fluid Tutorial In this tutorial we will solve a simple example using GiD and Kratos Geometry Input data and conditions PostProcess

3 DEFINING THE GEOMETRY

4 Geometry Rotate the view to plane XZ View > Rotate > Plane XZ Create domain and beam base Geometry > Create > Point Introduce the following points in the command line Press Enter after each point Beam Boundary box 0.0, 0.0, , 0.0, , 0.0, , 0.0, , 0.0, , 0.0, , 0.0, , 0.0, 0.7

5 Geometry

6 Geometry Now define the lines Geometry > Create > Straight line Ctrl + a Join the points of the beam base

7 Geometry Once finished, press Esc Create additional lines to define the boundary

8 Geometry Now we add the third dimension Utilities > Copy In the copy window, select Entities type: Lines Transformation: Translation First point: One of the beam corners Second point: Enter the same point but set y coordinate = 2 Do extrude: Lines Don t change the other options Press Select and mark the beam base

9 Geometry

10 Geometry Do the same for the boundary First point: (-2.0, 0.0, 0.7) Second point: (-2.0, 2.5, 0.7) You can rotate the view to check that the transformation worked

11 Geometry You can see that we are still missing some surfaces Geometry > Create > NURBS surfaces > By contour Select the top 4 lines of the beam and press Esc

12 Geometry Do the same for the top of the domain Geometry > Create > NURBS surfaces > By contour For the bottom of the domain, select the bases of the domain and the beam to take the hole into account

13 Geometry The final step is defining the volume Geometry > Create > Volume > By contour Select all surfaces and press Esc You can select all surfaces by drawing a box around the entire model

14 PROBLEM INPUT

15 Input data Load the Kratos problem type Data > Problem type > Kratos A new icon bar will appear

16 Define entity groups Click the Groups button to open the group window Each group will define a part of the model Fluid body Inlet surface Outlet surface Solid boundary Create a new group Click the New button Assign entities to a group Click the Assign button Choose an entity type

17 Define entity groups Fluid group Select the volume Inlet group Select the front surface Outlet Outlet group Select the back surface Fluid Wall group Select all remaining surfaces Inlet

18 Model Properties window Click the Properties button to open the properties window The tree contains all information about the model

19 Basic properties Path to your Kratos installation Set Fluid to Yes to run fluid simulations Choose the Fractional step solver You can use this option to choose a different solution algorithm

20 Solver properties Select an Iterative solver for velocity and pressure Set the analysis times: Start time: 0.0 End time: 2.0 Time step: 0.01

21 Fluid properties Create a new property for your fluid by selecting Properties Define a name for your property Assign a material (use default Water) Click Ok You can add or modify materials from the Materials tab

22 Element type Define the finite elements that will be used to mesh the domain Select Fluid elements A box that appears at the bottom Set the type to Tetrahedra Assign them the property defined in the previous step Assign the elements to the Fluid entity group we created earlier Click Ok

23 Boundary conditions Assign the boundary conditions using the surface entity groups First, assign the inlet condition Choose the Inlet velocity condition Assign it to the Inlet surface group The Activation tab is used to choose which velocity components we want to fix The Values tab is used to set the prescribed values Set the X value to 10.0

24 Boundary conditions Now assign the Outlet Pressure condition Set the pressure of the Outlet entity group to 0.0 Finally, assign a No-Slip condition to the solid boundary Select the Wall entity group Leave the three components active Leave all values at 0.0

25 Mesh the domain Mesh by selecting the menu option Mesh > Generate mesh On the box that appears, set size to 0.25 You can view the mesh using the View mesh button

26 Solve the problem Save your model Files > Save Launch Kratos with Calculate > Calculate The input data will be checked for errors A warning window will appear, as we didn t introduce some additional information. In this case, you can ignore it

27 Solve the problem You can check that the solution process is running properly using Calculate > View process info A window will pop up once the solution process finishes Click on Postprocess to view the results

28 SOLUTION POSTPROCESS

29 Post Processing Once the solution finishes, GiD will switch to Postprocess mode Alternatively, you can switch manually with View > Mode > Post Process By default, the results for your model will be loaded You can open other results with File > Open Common result formats are.post.bin binary results.post.res ASCII results.post.lst A list file pointing to multiple result files

30 Post Processing View the Pressure results with View results > Contour Fill > Pressure To view the interior of the model Windows > View Style In the View Style window, select Front Face culling

31 Post Processing Using Ctrl+m you see an animation of the results This is equivalent to Windows > Animate

32 Using cuts View the a result on an arbitrary plane using a cut Display velocity results with View results > Contour Fill > Velocity Define a cut using Do cuts > Cut plane > 3 points Use these points: -2.0, 1.25, , 1.25, , 1.25, 0.7

33 Using cuts To view just the cut Open the view style window Windows > View Style Turn off the light bulb next to Kratos View the time evolution with Ctrl+m

34 Thanks More Kratos at: Kratos webpage: Kratos wiki: Kratos tutorials:

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