Adaptive mesh refinement in MARIN's viscous flow solver ReFRESCO
Currently MARIN's viscous flow solver ReFRESCO is being improved by adding an adaptive meshing strategy. The method considers the mesh as an unstructured collection of elements and works with a database that defines different type of cell splits.

In principle the method copes with all kind of elements but we currently focus on splitting hexahedral elements in 2, 4 or 8 subcells. Anisotropic, or directional refinement is possible. The method is still in development but we demonstrate it here for two kind of flows using two different criteria for refinement: a feature-based criterion, the non-dimensional Q-criterion and an error estimator based on jump values.

The first test case is the 2D lid-driven cavity flow at Reynolds number 1000. The jump based error estimator using velocity magnitude or velocity and pressure gives good accuracy using about 25% of the cells compared to a uniform mesh. The Q-criterion is not working properly. It only increases the resolution in the vortex core without increasing the accuracy. The second test case is the flow around a wing at 10° incidence angle. For this test case the preliminary results show that with the jump based error estimator a significant improvement of the accuracy can be obtained with a very modest increase of number of cells. However, for this test case, no final conclusions about the performance of the jump based error estimator or the Q-criterion can be drawn yet.

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January 27, 2012
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