divergence-free velocity field - 2D problem
 

Hello,

I took the velocity gradients for the solution of 2D flow in the DEFINE_ADJUST() as below

dudx = C_U_G(c,t); dvdy = C_V_G(c,t);

DIV = dudx + dvdy;

and I obtained the values of DIV different than zero. How this is possible? Is there any kind of numerical error here?

Re: divergence-free velocity field - 2D problem
 

In order to complete my question I have to mention that the velocity gradients were defined in the following way:

dudx = C_U_G(c,t)[0]; dvdy = C_V_G(c,t)[1];

DIV = dudx + dvdy;

this results in non-zero values of DIV ?