CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Confusion Regarding Inlet Boundary Condition for Detonation Simulation

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 8, 2023, 04:27
Default Confusion Regarding Inlet Boundary Condition for Detonation Simulation
  #1
Member
 
Niyas
Join Date: Apr 2013
Posts: 45
Rep Power: 13
niyas is on a distinguished road
Hello everyone,

I am currently attempting to perform a numerical simulation of detonation within a 3D cylinder, as shown in Figure-1. However, I am facing some confusion regarding the definition of density and reactant density for the inlet boundary condition, as depicted in Figure-2.

Based on the literature review, I understand that I can use the equation of state, which is enclosed in a box within Figure-2. However, when I apply this method, I am observing a significantly high-density gradient at the wall (Figure-3). Since the wall has no inflow, shouldn't the density gradient be much lower? In other words, I expect the density gradient to be very minimal.

Would it be reasonable to use the same density gradient as the cells located next to the wall as an alternative? Does this sound like a logical approach?

Thanks,
Attached Images
File Type: png Figure-1.png (61.8 KB, 12 views)
File Type: jpg Figure-2.jpg (64.8 KB, 17 views)
File Type: png Capture.PNG (70.3 KB, 15 views)
__________________
Regards,
Niyas
niyas is offline   Reply With Quote

Old   March 8, 2023, 15:55
Default
  #2
Senior Member
 
Arjun
Join Date: Mar 2009
Location: Nurenberg, Germany
Posts: 1,286
Rep Power: 34
arjun will become famous soon enougharjun will become famous soon enough
I think the gradient that you see is because the solver is diverging. Try much smaller dt and see.
arjun is offline   Reply With Quote

Old   March 8, 2023, 19:06
Default
  #3
Member
 
Niyas
Join Date: Apr 2013
Posts: 45
Rep Power: 13
niyas is on a distinguished road
Thank you for responding.
The contour figures display the initial conditions at time zero, and I have not yet commenced the simulation. The computed density value is solely based on the boundary conditions depicted in Figure-2.
__________________
Regards,
Niyas
niyas is offline   Reply With Quote

Old   March 9, 2023, 02:40
Default
  #4
Senior Member
 
Arjun
Join Date: Mar 2009
Location: Nurenberg, Germany
Posts: 1,286
Rep Power: 34
arjun will become famous soon enougharjun will become famous soon enough
Then there are only 2 possibilities here.

1 you did not set it up properly (temperature and pressure)

2 software has a bug.

For bc i highly doubt that software has bug so carefully check how you are setting it up.

Walls shall have same density as near by cell.
arjun is offline   Reply With Quote

Reply

Tags
density gradient, detonation, inlet boundary condition


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
Error - Solar absorber - Solar Thermal Radiation MichaelK CFX 12 September 1, 2016 06:15
Problem with assigned inlet velocity profile as a boundary condition Ozgur_ FLUENT 5 August 25, 2015 05:58
An error has occurred in cfx5solve: volo87 CFX 5 June 14, 2013 18:44
Boundary condition setting regarding turbine simulation using CFX Lacerlacer CFX 11 March 12, 2012 10:32
RPM in Wind Turbine Pankaj CFX 9 November 23, 2009 05:05


All times are GMT -4. The time now is 21:21.