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-   -   MULTIBLOCK APPROACH (http://www.cfd-online.com/Forums/main/1567-multiblock-approach.html)

KAVEH ABDOLLAHZADEH November 23, 1999 04:24

MULTIBLOCK APPROACH
 
DEAR SIR I AM INTERESTED TO KNOW MORE ABOUT MULTIBLOCK APPROACH AS A MESH GENERATIG TOOL AND ALSO AS A SOLVING METHOD, AND IT'S ADVANTAGES.IS IT SUITABLE FOR 3-D MODELLIG OF FLOW IN THE DRAFT TUBE OF TURBINE? PLEASE DIRECT ME.

THANK YOU


John Chien November 25, 1999 18:25

Re: MULTIBLOCK APPROACH
 
(1). Structured multi-block mesh and the related solver basically is the same as the single block mesh, except in the booking of the individual block. (2). For example, a single block mesh of 60x40 can be divided into two blocks as 30x40 and 30x40. And the mesh can be created separately as if each is a single block mesh. (3). Since in this simple example, there is no internal boundary at i=30, the solver has to handle it as interior points, so that solutions can communicate with each block. That is the principle. (4). To eliminate this extra step, one can add extra mesh line from the joining mesh to the other mesh, to create overlapping region. In this way, the solution of the first block will include an extra mesh line solution, which will act as the boundary condition for the next block solution. You can use a couple of paper cards, with one edge of the card on the top of the other one, to give you a better picture. (5). If you slide one card upward such that only portion of the edge is overlapped, then it will represent a general multi-block mesh approach. (6). Using this principle, you can attach more cards (meshes) to the original cards, to create more complex multi-block mesh. (7). As you can see that, there is no extra cards ( or meshes) wasted (blank un-used). Thus, the computer memory is used effectively. (8). If one is not concerned about the memory, the structured multi-block mesh can be replaced be a conventional single block mesh. In this case, the solver avoids the region outside the internal boundary and the block-out region is not solved. (similar to a house with several locked un-used rooms) (9). So, for structured multi-block mesh and solver, it is fairly simple. You simply solve the multi-block mesh, block by block, each with an extra mesh line so that it will act as the boundary condition of the next block.


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