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

Model dimentsions when using cyclic boundary conditions

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 28, 2017, 06:18
Question Model dimentsions when using cyclic boundary conditions
  #1
Senior Member
 
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 10
RobertHB is on a distinguished road
Hello together,

According to de Villiers (2006), when using cyclic boundary condition in a plane channel flow the model dimensions should be restricted to a minimum of 4h*2h*2h length units in stream-wise and span-wise directions. This is supposed to ensure that the turbulence structures of the flow fit into the domain.

Now, my domain resembles a plane channel flow, but is only bounded by one plane (the lower boundary in an implementation of a solid topography) and my top boundary holds a slip condition. Furthermore, due to the scale of my domain (4*2*2 Ám) i do not observe any turbulence of the flow.

Question: When using cyclic boundary conditions for my case, do i need to stick to the above given restrictions to achieve a meaningful result, or do the dimension restrictions only apply to simulation which are supposed to simulate turbulence?

With regards,
Robert
RobertHB is offline   Reply With Quote

Old   August 28, 2017, 07:41
Default
  #2
Senior Member
 
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,290
Rep Power: 67
FMDenaro has a spectacular aura aboutFMDenaro has a spectacular aura aboutFMDenaro has a spectacular aura about
yes, the dimensions are evaluated for turbulent structures..in your case I think that such a low scale drive to a laminar flow
FMDenaro is offline   Reply With Quote

Old   August 28, 2017, 07:54
Default
  #3
Senior Member
 
Cees Haringa
Join Date: May 2013
Location: Delft
Posts: 607
Rep Power: 0
CeesH is on a distinguished road
your flow is certainly going to be laminar at those scales, so there should be no such restriction when solving a periodic domain. In fact, why do you want to CFD this? You could just take a 2-D (or 1-D, if you a have a wide channel) model from what I read, perhaps even an analytic solution.
CeesH is offline   Reply With Quote

Old   August 28, 2017, 08:33
Default
  #4
Senior Member
 
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 10
RobertHB is on a distinguished road
Dear CeesH,

the simulation is based on a 3D topography of a ceramic material after a dissolution experiment. The surface itself has a resolution of a few nanometers. We are investigating the near wall flow to determine if, on this scale, the surface roughness has an influence onto the flow. Trapping of the fluid within the pore space due to the formation of eddies is of great interest. At a later stage we aim to calculate the residence of our fluid and combine the information with a chemical model to improve the estimations of our lab experiments.

/edit: And yes, the flow is definitely laminar.
RobertHB is offline   Reply With Quote

Reply

Tags
channel flow, cyclic boundary condition, model dimension

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
Overflow Error in Multiphase Modelling with Two Continuous Fluids ashtonJ CFX 6 August 11, 2014 14:32
Water subcooled boiling Attesz CFX 7 January 5, 2013 03:32
RPM in Wind Turbine Pankaj CFX 9 November 23, 2009 04:05
Water vapour condensation in CFX-5.7.1 hdj CFX 1 November 27, 2005 07:15
Convective Heat Transfer - Heat Exchanger Mark CFX 6 November 15, 2004 15:55


All times are GMT -4. The time now is 00:14.