[Jeeloong]

Dear all,

I am pretty confused,

If I select domain of phase 2 (liquid) - I can display VOF as 1 for full liquid. and 0 means no liquid at all and Phase 1 VOF (1) will be display full air? right but different colour.

So I got a plane cut through the domain, I am interested to see if the velocity field has reached steady-state (from initial transient stage). So in the SURFACE MONITORS it says "Area-weighted Average" for example and DOMAIN OF

MIXTURE PHASE-1 PHASE-2. So which means in the plane, some part of the cells will be fully air and some part fully liquid and some interface (mixture)?

So if I get the "Area-weighted Avg" for velocity-magnitude and I plot a against time-step, and I selected mixture. Which means It will calculate all cell faces with MIXTURE (VOF 0 - 1) and compute the avg velocity-magnitude ? That is to say that the Velocity field of air is not computed otherwise the value will be greatly differ?

Am I right?

Thanks

Kind regards,
Jee Loong

[LuckyTran]

Originally Posted by Jeeloong

MIXTURE PHASE-1 PHASE-2. So which means in the plane, some part of the cells will be fully air and some part fully liquid and some interface (mixture)?

Each cell contains a MIXTURE consisting of motions of PHASE-1 and motions of PHASE-2. Every cell always contains something relating to PHASE-1 and something relating to PHASE-2. The MIXTURE properties is some weighted average of these two. In the VOF sense, there is no sharp interface and you cannot say this cell contains only PHASE-1 and none of PHASE-2. Every cell contains PHASE-1 and PHASE-2 even if the VOF is 1 (it may contain non-zero properties for PHASE-2 motions that are weighted by a very small VOF). Actually it cannot be exactly 1 because it is numerical, it will be something like 0.999999999999999999. There is no strict notion of fully liquid and fully air because all the solver knows is that there is some VOF.

Furthermore, there is no velocity field belonging to only air and another velocity field belong to the liquid (you do get such fields in a full Eulerian multiphase model) but the VOF approach does not do this. There is only one velocity field for the MIXTURE.