CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Density variations of a gas inside a chamber with hot plates

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 16, 2020, 03:10
Default Density variations of a gas inside a chamber with hot plates
  #1
New Member
 
Join Date: Jun 2020
Posts: 15
Rep Power: 2
KsaMe is on a distinguished road
Hi everyone,

I want to analize densities variations of a gas that is inside a chamber which has 2 rectangle hot plates (see picture 1). The plates are at a temperature of 1200K and the walls of the chamber are considered perfect insulators (heat flux = 0 as boundary condition). The gas inside is a mixture of 95% argon and 5% molecular hydrogen at an initial temperature of 300K.

I expect the density in the region between the plates decrease at first and then return to initial value. This because initially the air between the plates get rapidly hot (1200K) so this air has more temperature and more pressure than the air outside this region (surrounding regions). Due to the pressure difference this gas will flow out, carrying particles to the outside, and then decreasing its density. On the other hand, the surrounding region , which is cooler, receive this particles increasing its density and pressure. This process continues until the pressure of both regions get equal. Nonetheless there are heat conduction through the air, so the surrounding regions also get hotter with time, and if one wait a certain time it will reach 1200K. So now both regions has equal temperature, BUT the surrounding has more density, and hence more pressure. So now the flow will be into the space between the plates to restore the initial density.

When I did the simulation I considered the gas as an incompressible-ideal-gas, and was a mistake because it doesn't allow accumulation of particles, and I expect that initially particles will be acumulated in the surrounding regions of the plates. In fact it showed that the density of the chamber went down with time, clearly violating conservation of particles (see pictures 2 and 3). So then I changed the model of the gas to "Ideal-gas" and unfortunately the solution didn't converge (see picture 4).

I would really appreciate if someone could help me with some insight to solve this problem!

Best regards,

KSaMe
Attached Images
File Type: png Picture1(Chamber).png (17.9 KB, 5 views)
File Type: png Picture2(InitialDensity).png (48.6 KB, 7 views)
File Type: png Picture3(FinalDensity).png (48.7 KB, 7 views)
File Type: jpg Picture4(DivergenceOfSolution).jpg (130.8 KB, 8 views)
KsaMe is offline   Reply With Quote

Reply

Tags
density gradient, fluent, ideal gas

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
Natural Convection ! Boussinesq Vs Ideal Gas density cfd_user_pune ANSYS 4 September 15, 2020 09:46
heatTransfer solvers with high density variations pod OpenFOAM Running, Solving & CFD 0 March 25, 2019 10:05
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 13:02
gas species density faber Main CFD Forum 2 February 24, 2005 16:29
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 23:02


All times are GMT -4. The time now is 07:09.