/** Here we try to obtain a flow driven by a pressure drop on a tri-periodic cubic domain. Solution: since the pressure drop cannot be imposed in a periodic domain, the solution is to replace it with an equivalent body force i.e. we have in the r.h.s. of the momentum equation $$-\partial_x p + \rho a_x$$ so that adding a constant pressure gradient is equivalent to adding an acceleration $$a_x = - 1/\rho\partial_x p$$ */ #define LEVEL 6 #include "grid/octree.h" #include "navier-stokes/centered.h" #define rhoval 1000. #define muval 60. #define mydt 0.00375 #define maxiter (20) double deltau; scalar un[]; int main() { L0 = 1; DT = mydt; init_grid(1 << (LEVEL)); /* Tri-periodic flow driven by body force */ foreach_dimension() periodic(top); /* p[left] = dirichlet(0); p[right] = dirichlet(-10); */ const face vector dp[] = {10./L0/rhoval, 0, 0}; a = dp; run(); } event init (i = 0) { origin (0, 0, 0); /* set dynamic viscosity */ const face vector muc[] = {muval, muval, muval}; mu = muc; /* set density of the flow */ const scalar rhoc[] = rhoval; rho = rhoc; /* The flow is at rest initially. */ foreach(){ u.x[] = 0.; un[] = u.x[]; } } /* Logging the variable "deltau" that measures the difference between the current velocity to the initial one. */ event logfile (i++;i