Hello, everyone! I want to know if there is a bug in file mfix-19.1.2\model\des\calc_grad_des.f. On line 90 of this file there is a statement “del_phi(2,ijk) = calc_del_phi(flag(lo), flag(hi), &” whether the “2” should be replaced with “1”? 
Thank you for reporting the bug.
Gitlab issue #869
This bug will be fixed in the next point release (19.1.4).