Obtain a steady-state solution with only flow and turbulence equations selected. Using this result obtain the transient solution with energy and H2O eqs. selected. Best F. Saric

Dear Omid,

What is your time step size? If possible, try to reduce number of number of nodes (coarser mesh). It will help you to increase time step size and reduce total computational time in order to maintain same global Courant number.

Your mesh is very coarse. It is not advised to use parallel calculations below 150.000 200.000 elements or nodes ( it will depends on if  you are use Fluent or CFX, the methods have a subtle diference). This best practice is to avoid spend more time  in communication among then cores instead calculations ( the scalability ) . Hence,  it is indicated to use single instead parallel in this case. 

Well, 2.6GHz is good but is not faster. My older CPU has almost 7 year old it has 3.4GHz with a i7 from  2nd generation, and we have the 7th nowadays. The Xeon architecture is  wonder, but I thin yours is not the most newer. But is enough to manage your problem without problems. 

I've worked with multiphase problems there are 10 years.  10-20 days is common  to have a good result, generally the time scales are lo due a faster phenomena that must be captured. 

I'll repeat the ask from  Uday: whats is your time step?

hi thanks for your helping.

the time scale is adaptive according to courant No. and about in order to -4 (0.0001) and the simulation time is 60s.

Dear Recardo, when I use serial setting in fluent the simulation in too slow and I have to use parallel setting to use 100% of CPU power.

I think I can not coarse my grids because of the condensate water film must be form in condensation section and I have to use small mesh. The height of first mesh in near of wall is 0.05mm and the pipe diameter is 20 mm. The maximum aspect ratio of my grid is 5 and its ideal .

dear Fikret Saric sir i am also working on same phenomenon but i am facing problems. i can do the steady state evaporation but i am unable to do it in the transient solution.

Hello all

I have done the evaporation of diesel fuel droplets with transient dpm model . I suggest if u want to evaporate the droplets then do not couple vof with dpm.

Hi Ali,

If you are interested, I could send you Fluent case for the evaporation/condensation process. It is VOF two phase model with water and water vapor. If you have geometry you could send it. Best Regards, Fikret

I am doing the same type of problem i am trying to simulate the micro heat pipe in fluent, basically it is a heat pipe with condensation occurring at one end evaporation at other end and capillary forces due to change in curvature of vapour-liquid interface moves the fluid at corners from condenser section to evaporator and vapour move in central region

I have taken a 1000 micrometer pipe with 300mm of both evaporation and condenser section from both end and leaving 400 in between as adiabatic section

Problem I am facing while simulation is that the liquid is evaporating in evaporation section but not condensing in condenser section i am using the VOF model

I am new into all this any type of help is deeply appreciated, if any one can share the fluent case of evaporation/condensation process it will be of great help

Fikret Saric Omid Tutunchian

Akashdeep Gangrade

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increase condensation frequency in evaporation-condensation setting in Lee model.