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

Abt: Mach number.. Help! Plz!

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 5, 2008, 14:57
Default Abt: Mach number.. Help! Plz!
  #1
jinwon park
Guest
 
Posts: n/a
Hi all. Recently, I posted the question about the low-mach number flow simualation by the density-based formaluation. Today, I found a presentation material mentioning about this issue. The title is "The Low Mach number approximation for multidimensional modelling of type I-ray bursts". In that material, time step was increased by replacing delT=CFL*((dx)/(U+C)) by delT=CFL*(dx/U) when Mach <0.1. It sounds good for me who does not want to modify the equation as in preconditioning methods.

Have anyone see this approach? They said that this can speed up the computation by a factor of 10 or more. If so, it is a good one for me. In implementing, I had some questions about the Mach number. I know its definition but I could not realize some situations.

I am solving compressible gas-water flows. In initial stage, the flow velocity in rest water is zero. Wonder if Mach number is zero whenever the flow velocity is zero.Could you help me to figure out the numerical meaning of Mach number in simulations?

Thanks in advance!
  Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
SnappyHexMesh for internal Flow vishwa OpenFOAM Native Meshers: snappyHexMesh and Others 23 August 6, 2014 03:50
Mesh Refinement Luiz Eduardo Bittencourt Sampaio (Sampaio) OpenFOAM Mesh Utilities 41 January 17, 2013 03:43
Problem with decomposePar tool vinz OpenFOAM Pre-Processing 18 January 26, 2011 03:17
Strong oscillation at transonic mach number martingariepy FLUENT 2 May 12, 2009 11:40
Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 2 July 15, 2005 04:15


All times are GMT -4. The time now is 21:17.