# how to ?

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 February 14, 2003, 03:16 how to ? #1 prasat Guest   Posts: n/a hi, I have irregrular mesh I want too convert the mesh into regular mesh is it possible? or not

 February 15, 2003, 10:07 Re: how to ? #2 Praveen Guest   Posts: n/a More descriptive subject please ? There are ways to "regularise" grids. But when you say irregular/regular, what do you mean exactly ?

 February 17, 2003, 02:45 Re: how to ? #3 prasat Guest   Posts: n/a I mean I have irregular grid but I want to convert the grid into regular one.

 February 17, 2003, 03:25 Re: how to ? #4 Praveen Guest   Posts: n/a 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.

 February 17, 2003, 06:45 Re: how to ? #5 prasat Guest   Posts: n/a I am not sure may be the 1)You have a non-uniform grid which you want to map to a uniform grid. prasat

 February 19, 2003, 03:21 Re: how to ? #6 Praveen Guest   Posts: n/a 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.

 March 6, 2003, 15:21 Re: how to ? #7 Lluvia Marisol Flores Tandy Guest   Posts: n/a 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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