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Adaptive Meshing using STAR-CCM+. Weekly meeting – 05.12.2010 Victor Pépin. Plan. Curriculum Problem Software presentation Solution Results Next steps. Curriculum. Student at Ecole Centrale Paris French engineering school Non-specialized school 6 months internship in Manchester
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Adaptive Meshingusing STAR-CCM+ Weekly meeting – 05.12.2010 Victor Pépin
Plan • Curriculum • Problem • Software presentation • Solution • Results • Next steps
Curriculum • Student at Ecole Centrale Paris • French engineering school • Non-specialized school • 6 months internship in Manchester • February to mid-July
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
Software presentation • Star-CCM+, v4.04.011 (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”
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();
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)
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
Results 1/3 • 2D lid-driven cavity test case • Re = 50 • Steady state of the flow
Results 2/3 • 2D turbulent lid-driven cavity • Re = 15 000 • Establishing flow • The mesh follows the flow
Results 3/3 • 3D cylinder • Re = 10 • Flow entering the pipe on the left
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
Next steps • Measure the gains and loss of accuracy • Measure the benefits in terms of time, and memory
The end • Thank you for listening !