Basic Melting simulation

lsiva93 · February 20, 2015, 01:50

Hey everyone.

I am a newbie in CFD as well as ANSYS CFX. I am trying to understand hoe to apply boundary conditions and simulating flows.

Now, I am working on a simple simulation where an ice cube is placed on a tray. It is in vacuum because i don't want to complicate stuff by adding another fluid here.

I am done with the geometry and meshing.

I want to achieve the following result.

The heat transfers from the tray(25 deg C) at 100 W/m2
The ice cube at (-5 deg C) absorbs this heat and melts.

I actually want to see the "ice melt" and form a liqiud with free surface.

How should I proceed.

Thanks in advance

ghorrocks · February 20, 2015, 06:18

If you are new to CFD then a multiphase model with phase change is not the place to start. Your model is probably 3 phase actually - solid, liquid and gas - so definitely no for beginners. CFX does not have a built in model for melting or solidification so if you want to model it you have to generate the model yourself. CFX does have the flexibility to do this, but it is recommended for advanced users only.

You may not need to model the melting process. You could just generate liquid water at the melting interface - this would model the accumulation of liquid water. This model is still a multiphase free surface model so is not simple, but at least is more likely to be achievable for somebody new to CFD.

JuPa · February 22, 2015, 09:02

I laughed at the title. There is nothing basic about modelling what you want.

It is an absolutely difficult task to do - especially under a vacuum which many CFD solvers will fail to handle (a perfect vacuum does not exist).

Start at 1 bar pressure, and ramp the pressure down slowly. As you get to 100mbar and lower you'll begin to run to convergence difficulties (as if phase change isn't difficult enough as it is).

I suspect this project will take a long time for a newbie to CFD.

What information do you want CFD to provide to you?

February 20, 2015, 01:50	Basic Melting simulation	#1
lsiva93 New Member Sivaramakrishnan Join Date: Feb 2015 Location: Tamilnadu,India Posts: 2 Rep Power: 0	Hey everyone. I am a newbie in CFD as well as ANSYS CFX. I am trying to understand hoe to apply boundary conditions and simulating flows. Now, I am working on a simple simulation where an ice cube is placed on a tray. It is in vacuum because i don't want to complicate stuff by adding another fluid here. I am done with the geometry and meshing. I want to achieve the following result. The heat transfers from the tray(25 deg C) at 100 W/m2 The ice cube at (-5 deg C) absorbs this heat and melts. I actually want to see the "ice melt" and form a liqiud with free surface. How should I proceed. Thanks in advance

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February 20, 2015, 06:18		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	If you are new to CFD then a multiphase model with phase change is not the place to start. Your model is probably 3 phase actually - solid, liquid and gas - so definitely no for beginners. CFX does not have a built in model for melting or solidification so if you want to model it you have to generate the model yourself. CFX does have the flexibility to do this, but it is recommended for advanced users only. You may not need to model the melting process. You could just generate liquid water at the melting interface - this would model the accumulation of liquid water. This model is still a multiphase free surface model so is not simple, but at least is more likely to be achievable for somebody new to CFD.

February 22, 2015, 09:02		#3
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 15	I laughed at the title. There is nothing basic about modelling what you want. It is an absolutely difficult task to do - especially under a vacuum which many CFD solvers will fail to handle (a perfect vacuum does not exist). Start at 1 bar pressure, and ramp the pressure down slowly. As you get to 100mbar and lower you'll begin to run to convergence difficulties (as if phase change isn't difficult enough as it is). I suspect this project will take a long time for a newbie to CFD. What information do you want CFD to provide to you?