CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Heating up a water tank

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree4Likes
  • 1 Post By me3840
  • 1 Post By me3840
  • 1 Post By me3840
  • 1 Post By me3840

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 18, 2018, 10:40
Default Heating up a water tank
  #1
New Member
 
Thilo
Join Date: Oct 2018
Location: Germany
Posts: 10
Rep Power: 3
Seeth is on a distinguished road
Hi everyone!
I am new to CFD and Star CCM+ and trying to create a simulation of the heating process of a water tank. So far i have taken a surface model of the tank interior and extruded the internal volume. I have then split the extruded volume into 2 parts to have 1 volume for the water and 1 volume for the air above. I have also split the tank surface into a general interior surface and the heating module surface.
I have created a mesh continuum for the tank surface (only surface remesher) and a mesh continuum for the water and air (surface remesher, prism layer mesher, polyhedral mesher). I have also created a physics continuum for both water and air. Which physics models would be best to choose here?
Do i have to set up a physics continuum for the tank too (i have set one up but do i need it since the tank is only modeled as a surface?)?
Now i would like to set up the heating module surface as a constant heat source (1000 W) and set up the water and air boundaries so that i can see the convection currents in the water, at the water/air interface and in the air.
The heat convection through the solid wall of the tank doesn't really matter to me.
That´s really what I am struggling to do right now, any help is appreciated, thank you very much! I am adding a picture of my setup right now to help a bit with clarity.
Attached Images
File Type: jpg Tank.jpg (89.6 KB, 25 views)
Seeth is offline   Reply With Quote

Old   October 21, 2018, 03:46
Default
  #2
Senior Member
 
Join Date: Nov 2010
Location: USA
Posts: 1,229
Rep Power: 20
me3840 is on a distinguished road
No you don't have to model the solid of the tank. Just apply your heat condition to the appropriate surface of the fluid regions. You can delete the tank region, it's not needed.
Seeth likes this.
me3840 is offline   Reply With Quote

Old   October 21, 2018, 06:35
Default
  #3
New Member
 
Thilo
Join Date: Oct 2018
Location: Germany
Posts: 10
Rep Power: 3
Seeth is on a distinguished road
Thank you very much, I did that and it seems to work so far. Just have to optimize the mesh I think. Do you know the differences between the convection properties? "2nd" was setup as default, does that make sense in my case?
Seeth is offline   Reply With Quote

Old   October 21, 2018, 16:41
Default
  #4
Senior Member
 
Join Date: Nov 2010
Location: USA
Posts: 1,229
Rep Power: 20
me3840 is on a distinguished road
I think you're referring to the discretization scheme? In that case, yes 2nd order is what you want.

However I will add if you're not familiar with the basic discretization schemes and how they work, you need to do some reading on CFD basics. It's dangerously easy to get results out of a CFD code that are meaningless if you're unsure of what you're doing.
Seeth likes this.
me3840 is offline   Reply With Quote

Old   October 22, 2018, 08:07
Default
  #5
New Member
 
Thilo
Join Date: Oct 2018
Location: Germany
Posts: 10
Rep Power: 3
Seeth is on a distinguished road
Yeah, that's what I meant, thank you.
Yes, I know, I am doing that at the same time while working on this. I have a real model of the water tank to validate my results so that will definitely help me.

Since you helped me a lot already, could you give me your opinion on my physics continuum for the water region?

So far i have chosen:
Three Dimensional, Implicit Unsteady, Segregated Flow, Segregated Fluid Temperature, Liquid, IAPWS-IF97 (Water), Cell Quality Remediation, Laminar, Gradients, Gravity

Do i need the Boiling model even though I am not trying to reach a boiling temperature?
Seeth is offline   Reply With Quote

Old   October 22, 2018, 17:52
Default
  #6
Senior Member
 
Join Date: Nov 2010
Location: USA
Posts: 1,229
Rep Power: 20
me3840 is on a distinguished road
It's probably a better idea to do a steady simulation if you're new, they are more forgiving. It's very easy to get bad results from transient if you're not sure what you're doing.


If you don't expect boiling then no, you don't need boiling.
Seeth likes this.
me3840 is offline   Reply With Quote

Old   October 23, 2018, 04:04
Default
  #7
New Member
 
Thilo
Join Date: Oct 2018
Location: Germany
Posts: 10
Rep Power: 3
Seeth is on a distinguished road
Okay but my goal is to measure the time necessary to heat the water up to a certain temperature. Don´t I need a transient simulation for that purpose?
Thanks again for the help
Seeth is offline   Reply With Quote

Old   October 23, 2018, 04:31
Default
  #8
Senior Member
 
Join Date: Nov 2010
Location: USA
Posts: 1,229
Rep Power: 20
me3840 is on a distinguished road
Yes, you do need transient simulation for that. However transient simulations are expensive, hard to debug, and unforgiving for new users. You will find you can eliminate mistakes and learn much faster with a steady simulation. When you feel you have a grasp on things then move to transient.

It might also be a good idea to practice your transient simulation on a 2D or coarse 3D mesh (100k cells or so). It will take significantly less time to learn to do things properly that way. Make sure you understand how your solver settings, timestep, and number of inner iterations are affecting your solution, and learn to judge when timesteps are achieving enough convergence.

You will find it very easy to waste time doing long transient simulations like the one you want to do if you are new to things. Best start small and work up.
Seeth likes this.
me3840 is offline   Reply With Quote

Old   October 23, 2018, 06:11
Default
  #9
New Member
 
Thilo
Join Date: Oct 2018
Location: Germany
Posts: 10
Rep Power: 3
Seeth is on a distinguished road
Yes, that sounds very reasonable, I will try to follow that kind of workflow.
Thank you very much for all the good advice, it definitely helped me a lot so far!
Seeth is offline   Reply With Quote

Reply

Tags
convection, convection heat flux, heat and mass transfer, heating of fluid, star ccm+

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Filling Tank with Water leff CFX 7 August 21, 2017 07:47
[GAMBIT] Water Slosing in Water Tank iwan ANSYS Meshing & Geometry 4 October 17, 2013 18:25
Water subcooled boiling Attesz CFX 7 January 5, 2013 03:32
heating water in a bottle bigred OpenFOAM 3 August 21, 2009 06:10
Evaporating water from a tank Juan Catelén CFX 0 January 10, 2008 12:08


All times are GMT -4. The time now is 18:26.