Adaptive Meshing
using STAR-CCM+
Weekly meeting – 05.12.2010
Victor Pépin
Plan
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Curriculum
Problem
Software presentation
Solution
Results
Next steps
Curriculum
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Student at Ecole Centrale Paris
French engineering school
Non-specialized school
6 months internship in Manchester
• February to mid-July
Problem
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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
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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
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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
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If V > Vref :
• Create a box (Volume Shape), centred on the cell,
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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
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2D lid-driven cavity test case
Re = 50
Steady state of the flow
Results 1/3
Results 2/3
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2D turbulent lid-driven cavity
Re = 15 000
Establishing flow
The mesh follows the flow
Results 3/3
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3D cylinder
Re = 10
Flow entering the pipe on the left
Other features of the macro
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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…
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Refine the mesh considering several
field functions
Next steps
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Measure the gains and loss of accuracy
Measure the benefits in terms of time,
and memory
The end
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Thank you for listening !