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

How to calculte \Delta t from CFL?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 15, 2005, 18:37
Default How to calculte \Delta t from CFL?
  #1
Annie
Guest
 
Posts: n/a
Suppose the differential equation is a pure advection equation,

\fraction{\partial C}{\partial t} = u \fraction{\partial C}{\partial x}

And suppose CFL number is known, how to calculate time step \Delta t?

Thanks a lot.

Annie
  Reply With Quote

Old   March 15, 2005, 19:52
Default Re: How to calculte \Delta t from CFL?
  #2
agg
Guest
 
Posts: n/a
\Delta t = CFL* \Delta x

--------------

u
  Reply With Quote

Old   March 18, 2005, 03:12
Default Re: How to calculte \Delta t from CFL?
  #3
florin
Guest
 
Posts: n/a
For pure advection equation, the time step will be calculate from next relation: Dt=CFL*(Dx/u) where Dt is time step, Dx is spatial step, 0<CFL<1.
  Reply With Quote

Old   March 23, 2005, 09:05
Default How to Calculate Delta t for Incompressible prob?
  #4
Yousuf
Guest
 
Posts: n/a
In Compressible Flow Problem We calculate the Time step Value Using CFL Correlation. But in Incompressible Flow Problem How we calculate the Time step?.. What is the Physics Behind that?..

Thanks.... Yousuf
  Reply With Quote

Old   March 23, 2005, 10:48
Default Re: How to Calculate Delta t for Incompressible pr
  #5
Tom
Guest
 
Posts: n/a
If the flow is inviscid or you're using an explicit time integration scheme it is calculated exactly the same way in compressible and incompressible flows. The material derivative is a hyperbolic operator which implies a CFL restriction.
  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
CFL number in steady simulations Rol Main CFD Forum 4 August 20, 2010 09:17
CFL number for Navier-Stokes (Infinite? How large?) gory Main CFD Forum 6 April 30, 2009 19:51
Delta Wing Structured Grid Riaan FLUENT 3 December 31, 2004 13:03
CFL condition Sergei Main CFD Forum 2 October 13, 2004 15:38
CFL limits for separated flow Bigarella Main CFD Forum 3 August 11, 2002 07:22


All times are GMT -4. The time now is 16:58.