Multiphase flow through a porous medium

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Discussion Overview

The discussion revolves around simulating multiphase flow through a porous medium using the Volume of Fluid (VOF) method, focusing on phase change dynamics, specifically evaporation and condensation frequencies, and the challenges encountered in the simulation setup.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant is simulating flow through a porous medium with the VOF method and is uncertain about the evaporation and condensation frequencies, using a Lee Model for phase change.
  • The participant reports low temperature results and a flame that is distanced from the porous medium, despite using n-heptane as the liquid phase and having multiple species and reactions in the vapor phase.
  • Another participant expresses skepticism about the familiarity of others with such a specialized topic, indicating the potential difficulty in finding relevant expertise.
  • A participant describes a setup involving a capillary tube with specific dimensions and reports encountering divergence errors in pressure coupling, sharing solver settings and conditions.
  • One participant suggests contacting ANSYS support for assistance and questions the necessity of simulating both the heptane flame and evaporation within a single simulation, proposing that it may be more efficient to simulate them separately.
  • The original poster clarifies their use of VOF with two phases, mentioning confusion regarding the term "evaporation frequency" and expressing appreciation for any assistance offered.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the best approach to the simulation, with multiple competing views on the feasibility of simulating the heptane flame and evaporation together, as well as differing levels of familiarity with the specific technical aspects involved.

Contextual Notes

Limitations include potential missing assumptions regarding the simulation parameters, the complexity of multiphase interactions, and the unresolved nature of the divergence errors reported by participants.

william Alex
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I am simulating flow through porous medium with VOF method and species transport. For phase change i have Lee Model, and i have no idea about the evaporation frequency and condensation frequency
Second I am using the evaporation frequency as 30. The liquid is n-heptane while for vapour phase i have 25 species and 34 reaction.
I am getting results but the temperature is very lower and second my flame is away from the porous medium
 
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I suspect that this is such a hyperfocused question that the odds of anyone here being familiar with the topic are fairly slim.
 
boneh3ad said:
I suspect that this is such a hyperfocused question that the odds of anyone here being familiar with the topic are fairly slim.
Sir Let me explain.
I have a capillary tube with ID 0.2 mm. At inlet i give mass flux with liquid phase. At the exit of the capillary tube i define a region where i patch temperature. I am getting divergence error in pressure coupling etc.
My Solver setting as follow
VOF
Steady
Surface Tension
Species Transport Volumetric
Simple
URF are 0.2 to 0.3
 
what solver are you using? If it is from ANSYS you can contact them through the customer portal and ask their advice.

Just getting a solution for a single phase heptane flame will be a challenge, let alone simulating it together with the entire evaporation of the fuel in a porous medium. These multiphysics problems are usually spatially separated. Do you really need to simulate them inside a single simulation? Have you tried simulating only the heptane flame? Even for a skeleton mechanism like the one you are using, such a simulation can take quite some time.
 
bigfooted said:
what solver are you using? If it is from ANSYS you can contact them through the customer portal and ask their advice.

Well thanks for reply.
I am using VOF with two phase. The primary phase is my mixture imported from chemkin while my secondary phase is heptane liquid. for mass thransfer mechanism i am using lee model, but evaporation frequency is confusing term. I really appreciate your help.
 

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