I definitely need the Eulerian model (with DDPM phase) since my volume fraction is far beyond 15%.

I read through the guide again also section 1.9.1 and from my understanding I have 3 domains: mixture (ID 1), eulerian (gas) phase (ID 2, phase_domain_index 0), dpm phase (ID 3, phase_domain_index 1). TP_CELL_THREAD(tp) probably returns the Thread from domain 3 (DPM) so I need to first get a pointer to the mixture domain and then to the gas domain to read the gas velocity. I have tried that with the code below, but this still throws the error.

real uvel;

cell_t c;

c = TP_CELL(tp);

Thread *pthread, *gthread, *mixthread;

pthread = TP_CELL_THREAD(tp); //get particle thread

mixthread = THREAD_SUPER_THREAD(pthread); //get mixture thread

gthread = THREAD_SUB_THREAD(mixthread,0); //get gas phase thread; phase_domain_index of gas phase is 0

uvel = C_U(c,gthread);