[oberstar]

Disclaimer - this is my 2nd ever Ansys-Fluent simulation and I have not had any formal CFD training yet.

I am working on a simple ANSYS Fluent (16.2) multiphase flow simulation . The geometry is a larger straight tube with a smaller straight tube inside the larger one along the same axis with one end of each tube sharing the same plane.

I intend on having the the ring around the smaller tube defined as an inlet for one fluid type (Fluid 1) and the smaller tube an inlet for a 2nd fluid (Fluid 2) with the mixture coming out the far end. See attached model rendering.

I am at the point where I need to configure the Multiphase Model in Fluent and I am having difficulty identifying the correct model and parameters for the type of mixing model I hope to create. Fluid 1 will be a glycerol like fluid with a pulsatile flow up to 50cm/sec, and Fluid 2 will be a constant flow (or pulsatile flow) up to ~140 cm/sec of a homgeneous solution of specified concentration of an additive with a more syrup like viscosity. I am hoping to use the simulation to understand how Fluid 1 dilutes Fluid 2 farther down the pipe and how the net concentration varies over distance with the pulsatile mixing.

It appears from my searching I should use an Eulerian Multphase model based on page 8 of http://www.bakker.org/dartmouth06/engs150/14-multi.pdf and https://www.sharcnet.ca/Software/Flu...ug/node876.htm .

I can rule out enabling the boiling model and evaporation-condensation parameter options but I am unsure of whether to use Multi-Fluid VOF Model or Dense Discrete Phase Model in the Eulerian Parameters config window & If I do pick Multi-Fluid VOF how do I determine what to specify for the volume fraction cutoff and Courant Number?

Thanks in advance for any advice.

Erick

ConcentricTubeMultiphaseFlow-MeshedBodyOnly.jpg

Multiphase Model Window.png

Multiphase Model Window - Multi-Fluid VOF Model.png