even though i m using spacing=10 (Tgrid) the no. of cells generated while meshing a volume is a whopping 1299836!! Running this in fluent takes ages and i havent been able to find a way to reduce the no. of cells. Even a reference to some suitable book/document relevant to this problem would be very helpful.

Hi pooja, It depends on the units you are using to build your geometry. For example, if you are meshing a 1m long model and you use 'mm' while creating your model, you will have 1000 points in the direction of your length. So using a spacing of 10 will result in 100 points. Now for argument sake, if you have the same length , width and height, you will then have 100x100x100= 1000000 (10 lakh points!) for a hex grid. There's nothing wrong in giving a higher spacing (depending on the grid density you need) Try increasing your spacing and see if that helps! Also remember, meshing is processor AND memory intensive, so make sure your system has enough resources to handle the grid size you are trying to build. - Phil

I would like to mention one more point to phil's explanation: if you are using educational version of fluent then u have limitation on number of max cells u can go upto, example in my case its 1.2 million cells. u need to keep that in mind. and one more sugesstion is, make sure u have a fine mesh in the region where u want to resolve flow details. example for a pipe flow case, if u r studying go for a fully developed velocity profile at entrance using a udf, so tht u need not bother about wats happening along the flow, the flow variation is dramatic across the c/s area.