Computational Physics, Python, Math, Physics.
0.5*(q[1:N_x,1:N_y] + q[2:N_x+1,1:N_y])*(u_n[2:N_x+1,1:N_y] - u_n[1:N_x,1:N_y]) - 0.5*(q[0:N_x - 1,1:N_y] + q[1:N_x,1:N_y])*(u_n[1:N_x,1:N_y] - u_n[0:N_x - 1,1:N_y]) ) + Cy2*( 0.5*(q[1:N_x ,1:N_y] + q[1:N_x,2:N_y+1])*(u_n[1:N_x,2:N_y+1] - u_n[1:N_x,1:N_y]) - 0.5*(q[1:N_x,0:N_y - 1] +