Ghost cells
 

Hi

I am solving the 2D Incompressible N-S eq using the FVM. I have read that in order to set the Boundary Conditions I could use Ghost cells. How are this cells? How may I implement them?

Thanks in advance,

Ruben

Re: Ghost cells
 

Hi Ruben!! The ghost cells are nothing but the cells falling outside of boundary. In order to implement boundary conditions, you will need some cells outside the boundary. here is an example: suppose you want to write a central difference formula for d2U/dx= (Ui+1-2Ui+Ui-1)/(2dx). So when you will write this difference formula for cell 1. You will need a cell Ui-1. This cell will fall outside of the boundary. This cell is usally called as ghost cells. Ghost cells are determiined from boundary conditions. for example if your boundary is a solid wall, then you just this ghost cell to zero. Or you can get it by some interpolation in other boundary conditions. Hope this helps. Jaswant