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Old   February 14, 2003, 03:16
Default how to ?
  #1
prasat
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hi, I have irregrular mesh I want too convert the mesh into regular mesh is it possible? or not
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Old   February 15, 2003, 10:07
Default Re: how to ?
  #2
Praveen
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More descriptive subject please ? There are ways to "regularise" grids. But when you say irregular/regular, what do you mean exactly ?
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Old   February 17, 2003, 02:45
Default Re: how to ?
  #3
prasat
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I mean I have irregular grid but I want to convert the grid into regular one.

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Old   February 17, 2003, 03:25
Default Re: how to ?
  #4
Praveen
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1) You have a non-uniform grid which you want to map to a uniform grid. 2) You have a non-uniform grid which you want to smoothen (regularise). 3) You have an unstructured grid which you want to map to a uniform grid. 4) You have a BAD grid (bad angles, skewed cells, non-orthogonality) which you want to correct. 5) You just have an arbitrary distribution of nodes and you want to do something with that, maybe triangulate it.
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Old   February 17, 2003, 06:45
Default Re: how to ?
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prasat
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I am not sure may be the 1)You have a non-uniform grid which you want to map to a uniform grid. prasat
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Old   February 19, 2003, 03:21
Default Re: how to ?
  #6
Praveen
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Let (a,b) be the transformed coordinates and let da, db be the constant grid spacing in the computational plane. Mapping the grid is trivial

a(i,j) = i*da b(i,j) = j*db

Now you want to solve your pde on the transformed plane. So you must first transform your pde e.g.,

df/dx = (df/da)(da/dx) + (df/db)(db/dx)

Next you must approximate (da/dx), (db/dx), ...... using finite differences (since you do not have exact transformation relations). It is easier to calculate (dx/da), ........ rather than the above quantities. For example

(dx/da)_(i,j) = [ x(i+1,j) - x(i-1,j) ]/da

Using these and some more formulae which you can find in a cfd book you can estimate the required transformation coefficients.
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Old   March 6, 2003, 15:21
Default Re: how to ?
  #7
Lluvia Marisol Flores Tandy
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HI!

I HAVE A PROBLEM, I WAS TRYING TO FIND THIS PAPER FOR A LONG TIME AND I COLDNīT GET IT.

SOMEONE CAN HELP ME?

THANK YOU

de Vahl Davis, G., "Natural convection of air in a square cavity: a bench mark numerical solution", Int. J. Num. Meth. in Fluids, Vol. 3, pp249-264 (1983).

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