{"id":285821,"date":"2023-05-25T19:11:40","date_gmt":"2023-05-25T19:11:40","guid":{"rendered":"\/forum\/forums\/topic\/transient-packed-bed-simulation-with-counter-flow-orientation-and-two-phases\/"},"modified":"2023-05-25T19:13:50","modified_gmt":"2023-05-25T19:13:50","slug":"transient-packed-bed-simulation-with-counter-flow-orientation-and-two-phases","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/transient-packed-bed-simulation-with-counter-flow-orientation-and-two-phases\/","title":{"rendered":"Transient packed bed simulation with counter-flow orientation and two-phases"},"content":{"rendered":"

Hi all,<\/p>\n

I am simulating a transient counter-flow two phase packed ped using the Eulerian-Eulerian multiphase model. The geometry and boundary conditions are listed below.<\/p>\n

<\/a>
<\/p>\n

Bottom of domain ( z = 2.205m) pressure-outlet<\/strong> with the back flow volume fraction 1 for the gas phase<\/p>\n

Top of the domain (z = 0 m) Velocity-Inlet <\/sub> <\/strong>was placed with velocity of the gas phase as -0.25 m\/s and a volume fraction of 1 for the gas phase.<\/p>\n

Note<\/strong> these boundary conditions were instated to force the gas phase to enter the domain from the bottom uniformly.<\/p>\n

Wall conditions<\/strong> for the walls.<\/p>\n

At the liquid sparger a Velocity-Inlet<\/strong> was placed, with velocity of the liquid phase as 0.038 m\/s and a volume fraction of 1 for the liquid phase.<\/p>\n

 <\/p>\n

This simulation iterates nicely up until the liquid phase enters the packed bed which is ~ 0.08 [m] from the top , as seen in the picture.<\/p>\n

 <\/p>\n

The simulation diverges because in the packed bed domain, which was spliced in design space, a fluid dispersion momentum source term is introduced, see below.<\/p>\n

<\/a><\/p>\n

<\/a><\/p>\n

<\/a><\/p>\n

<\/a><\/p>\n

<\/p>\n\n\n\n\n
 <\/td>\n<\/tr>\n
 <\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

 <\/p>\n

Most of these variables on constants, so the only variable that may cause issues is the division of volume fraction. So to avoid 1\/0 in the source term I enforced a conditional statement with a volume fraction tolerance, see below.<\/p>\n

<\/a><\/p>\n

 <\/p>\n

However, my simulation still diverges when the liquid enters the packed bed domain. I have done a thorough investigation and found that my simulation works if the source term is removed. The fluid flows freely into the packed bed domain.<\/p>\n

Other key simulation parameters:<\/p>\n

1.       <\/span>When initializing the gas phase occupies the entire domain<\/p>\n

2.       <\/span>Implicit Volume fraction parameters<\/p>\n

3.       <\/span>Time step is 1e-04<\/p>\n

4.       <\/span>Mesh size: Cells – 144,488, Faces – 365,148, Nodes – 83,839<\/p>\n

5.       <\/span>I have tried to refine the mesh at the interface ( still diverges)<\/p>\n

So what does the community suggest?<\/p>\n","protected":false},"template":"","class_list":["post-285821","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t