February 6, 2023 at 12:49 pm
Yannik Danner
Subscriber

Nice, thanks for these information.

I am trying to simulate a bubble column via multiphase eulerian-eulerian method in combination with inhomogeneous discrete or DQMOM population balance modeling. I am using 3 secondary air phases and a primary water phase.

Particle size range: (0.0015 -0.0095 m). For the initial BC i wanna check three dfferent superficial velocities: 2.5 mm/s, 12 mm/s and 22 mm/s. I am calculation PSD extern with log. normal distribution to split the inlet velocity to the three phases (its recommendes to use inlet vof = 0.5 for inlet BC).

I tried to use these DQMOM-method like u said. Cases with same operation conditions worked for QMOM and without PBM (3 and 1 sec. Phases). When using DQMOM simulation runs for low superficial velocity (2.5) at inlet. When using higher superficial velocity i get very high continuity residual (4.5475e+59) and floating point exception:

 Stabilizing mp-x-momentum to enhance linear solver robustness.
        Stabilizing mp-x-momentum using GMRES to enhance linear solver robustness.
        Stabilizing mp-y-momentum to enhance linear solver robustness.
        Stabilizing mp-y-momentum using GMRES to enhance linear solver robustness.
        Stabilizing mp-z-momentum to enhance linear solver robustness.
        Stabilizing mp-z-momentum using GMRES to enhance linear solver robustness.
        Stabilizing k to enhance linear solver robustness.
        Stabilizing k using GMRES to enhance linear solver robustness.

Divergence detected in AMG solver: k        Stabilizing vof-2 to enhance linear solver robustness.
        Stabilizing vof-2 using GMRES to enhance linear solver robustness.

Divergence detected in AMG solver: vof-2
 turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 4500 cells 

Error at host: floating point exception

Error at Node 0: floating point exception

Error: floating point exception
Error Object: #f

Same Error while using inhomogeneous discrete method for same PSD. Is there something to consider in inlet BC spliting inlet velocity and volume fractions? I am not able to explain why discretization might be this mad for these setup when other velocitys or methods are running.