Learning Forum

[prashant]

I WANT TO SIMULATE THE FLOW OF LIQUID NITROGEN THROUGH A NOZZLE, I AM FACING DIFFICULTY IN INCORPORATING PHASE CHANGE MECHANICS WHEN LIQUID NITROGEN IS INSIDE THE NOZZLE AS WELL AS WHEN IT IS COMING OUTSIDE.

[DrAmine]

Which solver are you using? Which models are you deploying?

[seeta gunti]

Hello Prashant,

We have multiple video tutorials on phase change in You tube. I recommend to go through them also very difficult to understand your problem with not much information on problem description. You can add few images describing your geometry and modeling aspects.

[prashant]

thanks for you kind support 

i am  attaching the geometry and properties 

kindly specify how to model this,i have planned to use second order upwind, with pressure correction scheme.k-epsilon turbulence model and energy equation would be solved simultaneously.is their anything else required?nozzle hole is 0.8 mm.

[Rob]

You're going to need a very fine mesh and small timestep for this as the liquid is going to flash boil. Start with an isothermal VOF jet to understand the mesh requirements and progress from there.  As Seeti mentions we have phase change tutorials, and you also want to look at the VOF model: read up on the Fluent documentation too as you need to understand the model limits and requirements. 

[Karthik R]

Hi Prashant,

Just to add to rwoolhou's comments, you can use the k-Eps turbulence model to solve your problem. However, I do not think that is going to be the bottleneck. As mentioned by rwoolhou, you will have to check if you are getting reasonable results using VOF. Getting your VOF model up and running will take some effort.

I'd strongly recommend a literature review before jumping into the model. You might get some test problems to play with before attempting to solve your problem - just to get the ball rolling in the right direction.

please let us know if you have any additional questions.

Best Regards,

Karthik

[prashant]

I am using VOF(3 phases liquid nitrogen, water, air) along with solidification and melting model, keeping k-epsilon for turbulence, but since the velocity at inlet is 70 m/s ,so I have to choose very low time step(0.0000001) in order to satisfy the courant number. Refining mesh increase the computation time. Selecting implicit scheme (in VOF) is not giving the proper result. SUGGEST ANY REMIDY TO DECRESE THE COMPUTATION TIME.

WHY CAN'T WE USE IMPLICIT WITH VOF?