Hi,all

I have to simulate a water/vapour system. There is phase change between the two material. I have no experience about it. Could you give me some advice.

A simple example is better.

What do you want to model: dropwise condensation (heterogeneous or homogeneous) or condensation on a surface? Is it pure steam or water vapor in a gas(mixture).

Hi, Bart Prast. I want to model dropwise condensation, and gas phase is pure water vapour.

Thank you.

http://www.cfd.com.au/cfd_conf03/papers/148Jon.pdf

This shows a little but on what we are doing on that subject

You have three choices for this in CFX-5.7:

- Equilibrium phase change model. Assumes homogeneous velocity, homogeneous energy, infinite mass transfer rate. liquid mass fraction is calculated based on mixture enthalpy and pressure, which are both calculated by the flow solver.

- Eulerian Multiphase with the thermal phase change model. I suggest you run homogenous mass and momentum, inhomogeneous energy with the two resistance heat transfer model. Set the droplet side heat transfer to zero resistance, and the vapour side heat transfer to a Nusselt number or maybe one of the particle based heat transfer model. This has the limitation that the droplet diameter is fixed. You may have to play with the vapour side heat transfer model to get the right thing happening.

- Lagrangian Multiphase with custom mass transfer model. This is similar to the above but you will have to code up your condensation mass transfer rate on your own. Does not have a droplet diameter limitation like Eulerian does but it's not as efficient in parallel runs.

if it possible, send a tutorial or help me to simulate a simple boiling phenomena, thank you

describe more clearly, please. i do some research as you

BR, Erica

if it possible send for me a simple tutorial of simulating a boiling phenomena, thank you

[yxgayy]

Originally Posted by Neale
;70449

You have three choices for this in CFX-5.7:

- Equilibrium phase change model. Assumes homogeneous velocity, homogeneous energy, infinite mass transfer rate. liquid mass fraction is calculated based on mixture enthalpy and pressure, which are both calculated by the flow solver.

- Eulerian Multiphase with the thermal phase change model. I suggest you run homogenous mass and momentum, inhomogeneous energy with the two resistance heat transfer model. Set the droplet side heat transfer to zero resistance, and the vapour side heat transfer to a Nusselt number or maybe one of the particle based heat transfer model. This has the limitation that the droplet diameter is fixed. You may have to play with the vapour side heat transfer model to get the right thing happening.

- Lagrangian Multiphase with custom mass transfer model. This is similar to the above but you will have to code up your condensation mass transfer rate on your own. Does not have a droplet diameter limitation like Eulerian does but it's not as efficient in parallel runs.

can you explain about Lagrangian with condensation in detail? Have you done it successfully? I want to do it but i do not how to do ?? can you tell me your email ,my email is yxgayy@126.com. Thank you!

[yxgayy]

Originally Posted by Bart Prast
;70341

What do you want to model: dropwise condensation (heterogeneous or homogeneous) or condensation on a surface? Is it pure steam or water vapor in a gas(mixture).

have you ever simulated heterogeneous condensation successfully using CFX ?? I have problem in setting in CFX, I think just set the user defined nucleation rate is not appropriate, it just treats the droplets formed by heterogeneous condensation as a spherical ball, not a spherical cap.Can you tell how you handle it.Thanks a lot in advance!