CFD Online Discussion Forums - Separate phase data in DPM_SCALAR

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Separate phase data in DPM_SCALAR_UPDATE

I have an eulerian multiphase model with 2 phases, and am using a DPM to track particles in the flow. I want to lookup variables about the cell a particle is in, but cannot return any involving the second phase, only the primary. I need both but can't access them and it feel like it should be obvious. I use the following code:

PHP Code:


		
			
DEFINE_DPM_SCALAR_UPDATE(activation_potential,cell,thread,initialize,p)

{

    int n_cphases = 2; /* Both phases interact with DPM */

    cphase_state_t* c = &(p->cphase[0]); /* Gets the cell the particle is in - I thought [0] specified primary phase but not sure */

   if (initialize)

    {

      /* this is the initialization call, set:

     * P_USER_REAL(p,0) contains the activation potential, initialize to 0.

     * Variables 1-3 Contain the Viscosity, Strain and Volume fraction of the Primary (Continuous) Phase*/

      P_USER_REAL(p,0) = 0.;

      P_USER_REAL(p,1) = c->mu;

      P_USER_REAL(p,2) = c->strain_rate_mag;

      P_USER_REAL(p,3) = c->cont_phase_vof;

     }

  else

    {

      /* Activation potential is: Exposure time * Strain rate * Viscosity * Volume Fraction */

      P_USER_REAL(p,0) += P_DT(p) * P_USER_REAL(p,1) * P_USER_REAL(p,2) * P_USER_REAL(p,3);

     /* save current values for start of next step */

      P_USER_REAL(p,1) = c->mu;

      P_USER_REAL(p,2) = c->strain_rate_mag;

      P_USER_REAL(p,3) = c->cont_phase_vof;

     }

}

Which I then write using DPM_OUTPUT and works fine for giving values of viscoisty,strain etc for the primary phase but nothing I try gives these values for the secondary phase! I've tried:

PHP Code:


		
			
cphase_state_t* c = &(p->cphase[1]);

And about every other number there and it outputs 0 for everything. I've looked through the "cphase_state_struct" in "dpm_types.h" and can't find anything on how to ask for this for other phases.

Any tips?

Found out how to get the variables I wanted in the less dodgy way with the code below. Ensure you tell it to allocate 6 scalars when you hook the Scalar_DPM UDF otherwise you'll get a SIGESV bullshit error.

PHP Code:


		
			
DEFINE_DPM_SCALAR_UPDATE(scalar_calc,cell,thread,initialize,p)

{

    cell_t c = P_CELL(p); /* Define cell particle is in */

    Thread *t = P_CELL_THREAD(p); /* Thread particle is in (General thread - not a phase thread!) */

    Thread** pt; 

    pt = THREAD_SUB_THREADS(t); /* Pointer to the phase thread within general thread - [0] - Primary and [1] - Secondary*/

  if (initialize)

    {

      P_USER_REAL(p,0) = C_MU_EFF_MIXTURE(c,t,pt,0); /* Plasma Viscosity */

      P_USER_REAL(p,1) = C_MU_EFF_MIXTURE(c,t,pt,1); /* RBC Viscosity*/

      P_USER_REAL(p,2) = C_VOF(c,pt[0]); /* PLASMA VOF */

      P_USER_REAL(p,3) = C_VOF(c,pt[1]); /* RBC VOF */

      P_USER_REAL(p,4) = C_STRAIN_RATE_MAG(c,pt[0]); /* Plasma Strain */

      P_USER_REAL(p,5) = C_STRAIN_RATE_MAG(c,pt[1]);  /* RBC Strain */

      P_USER_REAL(p,6) = 0;  /* Initial Variable for Activation Potential */

    }

  else

    {

      P_USER_REAL(p,0) = C_MU_EFF_MIXTURE(c,t,pt,0);

      P_USER_REAL(p,1) = C_MU_EFF_MIXTURE(c,t,pt,1);

      P_USER_REAL(p,2) = C_VOF(c,pt[0]);

      P_USER_REAL(p,3) = C_VOF(c,pt[1]);

      P_USER_REAL(p,4) = C_STRAIN_RATE_MAG(c,pt[0]);

      P_USER_REAL(p,5) = C_STRAIN_RATE_MAG(c,pt[1]);

      /* Calculation of Activation Potential at each particle step */

      P_USER_REAL(p,6) = P_DT(p) * (P_USER_REAL(p,0) * P_USER_REAL(p,2) * P_USER_REAL(p,4) + P_USER_REAL(p,1) * P_USER_REAL(p,3) * P_USER_REAL(p,5));

    }

}