MUSCL shock capturing on high aspect ratio meshes

vijay_paul · September 28, 2012, 15:21

I have noticed that MUSCL generates oscillations (non-monotone behavior) behind oblique shocks if the mesh aspect ratio is high. The problem does not seem to occur near walls where structured meshes have very high aspect ratios. There are situations like backward facing step problem where downstream of the corner, mesh is highly anisotropic. If the shock is at an angle of 45 degrees and aspect ratio is 10, then shock will be 2-3 points wide in one direction and 20-30 points in the other. When the limiter tries to sharpen the shock front in latter direction, one ends with a stair case shaped shock and post shock oscillations. Any thoughts on this other than the simple suggestion of avoiding high anisotropy will be greatly appreciated.

praveen · September 29, 2012, 01:16

Your mesh is not able to resolve the shock. There is not much that can be done in this case, other than to adapt your mesh.

Using a higher order method like weno might help to some extent.

September 28, 2012, 15:21	MUSCL shock capturing on high aspect ratio meshes	#1
vijay_paul New Member Vijay Paul Join Date: May 2011 Posts: 4 Rep Power: 15	I have noticed that MUSCL generates oscillations (non-monotone behavior) behind oblique shocks if the mesh aspect ratio is high. The problem does not seem to occur near walls where structured meshes have very high aspect ratios. There are situations like backward facing step problem where downstream of the corner, mesh is highly anisotropic. If the shock is at an angle of 45 degrees and aspect ratio is 10, then shock will be 2-3 points wide in one direction and 20-30 points in the other. When the limiter tries to sharpen the shock front in latter direction, one ends with a stair case shaped shock and post shock oscillations. Any thoughts on this other than the simple suggestion of avoiding high anisotropy will be greatly appreciated.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[ICEM] check aspect ratio	camoesas	ANSYS Meshing & Geometry	2	November 14, 2011 10:38
[ICEM] Mesh along axis for a wedge gives elements with extreme aspect ratio	sangrampp	ANSYS Meshing & Geometry	0	November 17, 2010 07:57
flow with high turbulent viscosity ratio	Phillips	Main CFD Forum	2	August 25, 2008 19:01
High aspect ratio in viscous sublayer?	Marius	Main CFD Forum	0	December 22, 2005 09:15
high aspect ratio elements	Olivier	CFX	5	April 3, 2003 07:55

September 29, 2012, 01:16		#2
praveen Super Moderator Praveen. C Join Date: Mar 2009 Location: Bangalore Posts: 343 Blog Entries: 6 Rep Power: 18	Your mesh is not able to resolve the shock. There is not much that can be done in this case, other than to adapt your mesh. Using a higher order method like weno might help to some extent.