i am solving fluid (water) flow past circular cylinder (2D). i am genertaing the grid in gambit. i want my grid to be logrithmic i.e dense near the body and spreadout as we move away from the body as i need better resolution near the body surface. Can anyone suggest how to do this. Thankyou.

no problem: you first mesh the edge that defines your cilinder. Do it with a fine spacing. Then you use a pave scheme with a larger setting for the spacing for the entire surface. Your meshed edge will force the mesh to be finer near the cilinder. Play around with the settings to get a feel of it.

Other possibility: Use (Gambit2.0) the sizing functions.

You can also apply a boundary layer on the surface of your cilinder to obtain a good mesh near the surface to capture the high gradients in that region (recommended!)

greetings,

Laika, still orbiting

Laika, is right. But if you haven't done this before it can be tricky. Seperate your domain around the cylinder into 4 areas. Mesh the edges (I believe there is a logarithmic biasing function availabe when meshing edges), Then mesh each face.

Can I ask why you want to use a logarithmic scheme?

Chetan & Laika,thanks for your response.

Chetan, i wanted to use logarithmic scheme because i have myself wrote a programme for soving this problem there i transformed cartisian coordinates into logrithmic spherical coordinates to obtain rectangular domain with closer spacing near the cylinder surface something like x=theta and y=log(r), where theta is angle and r is radial distance. i just wanted to see if such grid was possible. In anycase it need not be logarithmic only it should dense near surface. i will try what u and Laika told. bye