1. Adaptive Meshing using STAR-CCM+
Weekly meeting –
Victor Pépin

2. Plan Curriculum Problem Software presentation Solution Results
Next steps

3. Curriculum Student at Ecole Centrale Paris French engineering school
Non-specialized school
6 months internship in Manchester
February to mid-July

4. Problem
How to improve the use of computation resources over the geometry of the simulation ?
Particularly, how to share resources relevantly, depending on the interest each area of the simulation represents ?
A solution : adaptive meshing

5. Software presentation
Star-CCM+, v (CD-Adapco)
Allows the use of macros, written in Java
A macro is a list of instructions, forming an algorithm
It interacts with the software via the user interface
The software is seen like a “black box”

6. Example of macro instructions
// Define the simulation as a variable
Simulation simulation_0 = getActiveSimulation();
// Define the Stopping Criterion as a variable
StepStoppingCriterion stepStoppingCriterion_0 =
((StepStoppingCriterion) simulation_0.
getSolverStoppingCriterionManager().
getSolverStoppingCriterion("Maximum Steps"));
// Set the value of the Stopping Criterion to 1000
stepStoppingCriterion_0.setMaximumNumberSteps(1000);
// Run the simulation
simulation_0.getSimulationIterator().run();

7. Solution Scheme 1/2
Choose a quantity of interest, which will be the criterion of your refinement: e.g. velocity
Launch the simulation with a coarse mesh
Export a table containing the velocity in each cell of the mesh
Consider each cell, and compare its velocity with a reference velocity
Vref = Vmin + percentage x (Vmax – Vmin)

8. Solution 2/2 If V > Vref :
Create a box (Volume Shape), centred on the cell, whose size is approximately the size of the cell
Add the Volume Shape to a Source Volume
Set a smaller base size for the mesh upon the Source Volume
Re-mesh the simulation
Run the simulation
Repeat the process

9. Results 1/3 2D lid-driven cavity test case Re = 50
Steady state of the flow

10. Results 1/3

11. Results 2/3 2D turbulent lid-driven cavity Re = 15 000
Establishing flow
The mesh follows the flow

12. Results 3/3
3D cylinder
Re = 10
Flow entering the pipe on the left

13. Other features of the macro
Adapt easily to any case (shape, boundaries, type of mesh…)
Take user-defined field functions as a criterion for mesh refinement
Gradients,
Convergence between 2 times steps…
Refine the mesh considering several field functions

14. Next steps Measure the gains and loss of accuracy
Measure the benefits in terms of time, and memory

15. The end
Thank you for listening !