Hello, I would like calculate derivative: d/dx(mi(dVz/dz)) where, dVz/dz is derivative velocity (C_DWDZ(c,t)) mi is viscosity (C_MU_L(c,t)). How in Fluent calculate derivatives of d/dx, d/dy and d/dz.

Thanks, for your help Best regards Tomik .

Define a UDSI as (C_UDSI(c,t,0) = mi(dVz/dz)) and then allocate C_UDSI_G.In postprocessing and also turn off solution of UDSI's in solve\controls menu , value of C_UDSI_G [0] is equal to d/dx(mi(dVz/dz)) .