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gman89 May 11, 2011 23:01

ICEM: Projectile Meshing and Modelling Issues
3 Attachment(s)
Hi everyone,

I'm trying to solve problems for a projectile and at the moment I'm just undertaking a simple 2D meshing of the geometry.

Because of the features, generally I have a couple blocks around the geometry which include the nose, middle section and boat-tail at the end. I have also split the O-grid near the geometry to allow higher accuracy close to the surface of the projectile. (see image 1 for layout)

My problem is that at the boat-tail, there is a glitch as the inner more refined section seems to have either less node points, or a mis-alignment between them as shown in image 2. In problem area where the mesh is only one element wide, I've tried splitting that block to see what effect it would have but it stayed the same more or less. I've also tried disassociating a couple of the edges from the geometry and ensuring that was correct but that didn't seem to have any effect.

I tried to work around the problem by angling the left hand boundary of the block so there was an easier transition. The problem was that when I refined this mesh using orthogonality, it resulted in an obscure mesh at the rear of the geometry whilst making it smoother at the initial problem area as shown in image 3.

Any help on this would be appreciated.

I have other non-related questions on this problem as a whole which aren't that essential but:

1) If I am to keep this 2 dimensional, how would I set up the model in ANSYS? Do I use one symmetry plane on the facade shown in the images? Or is there a way of making this axisymmetric? Is splitting my current mesh in half horizontally through the center a valid option?

2) If the airspeed around the geometry is about Mach 0.7, how many iterations and time steps should I use such that the he wake is fully developed?

Any information would be great, thanks again.

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