Dear Friends,

i have been solving a problem which concerns with potential distribution across anode-cathod system.i have calculated the laplace euation for potential(c1) by activating only diffusive terms.this gives the values of potentials at each cell center.now i want to calculate the current by calculating gradient of potential multipled by electrical conductivity.how can i get the current at cell face not at the center?Is the value of potential same in the cell everwhere?

Hi,

Yes the value of potential is considered constant over the entire cell.

Maybe one way of doing this is to use linear interpolation to calc the potential at the cell face. The gradients of this potential will then be situated at the cell centers from which you can then interpolate back to the cell faces.

This might be sensible as if you are to calculate Lorentz forces, you will wish the magnetic field and current density values to occupy the same position when you calculate the JxB term.

Linear interpolation : a*C1(Y+1)+b*c1(Y)/(a+b); where a is dist of cell center(at y) to edge of cell and b is dist of cell center(at y+1) to edge of cell.

Phoenics provides indexes for ground access to distances between walls of continuity cells (dyv2d etc) obviously these distances /2. give distances from the cell center to the wall, i.e. the "a" and "b" mentined above.

Dear Mick,

thanks for your much needed help.as you suggested, i had calculated the current at the cell face by simple interpolation.my results are not fully satisfactory.If you could tell me some more like when i am solving the laplace equation for potential distribution by activating the diffusion term in TERMS in Q1,do i need to give the coefficient K(in this case electrical conductivity of the specified region,as my K is constant) by setting PRANDTL=-GRND and specifying the values in ground file.can you suggest any libarary case as i can find only one which calculate Loretz force in hall cell.

with regards,

Rohit Kumar