Which scheme has been used to discretize the convective term in this equation:FeϕE−FwϕP=De(ϕE−ϕP)−Dw(ϕP−ϕW){"version":"1.1","math":"F_e\phi_E-F_w\phi_P=D_e\left(\phi_E-\phi_P\right)-D_w\left(\phi_P-\phi_W\right)"}