Interpolation related issue

Kana

Hi Everybody,

I try to trace particles in a reactor. Here the fluid flow is solved by FVM, and the motion of particle is solved by Lagrangian method. In order to calculate fluid drag force acting on particles, it requires the fluid velocity on particle position which is usually stored in the centre of CFD cell. Suppose I have already known the host cell where a considered particle is residing. Which method should be the best choice to obtain the fluid velocity on particle position from around CFD cells? For a quadrangular grid (2D), should I consider 9 cells (1 host cell + 4 neighboring cells + 4 immediate neighboring cells), or just 5 cell (1 host cell + 4 neighboring cells)?

Your suggestions would be greatly appreciated?

Regards,

Kana