|
[Sponsors] |
Rayleigh Benard 3D coding with finite differences |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
February 17, 2016, 00:16 |
Rayleigh Benard 3D coding with finite differences
|
#1 |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
I am developing a simple fortran solver in finite difference. My domain is 2pi*2pi*1 as taken by S. Chandrasekhar. My equations are having non dimensional parameters as Reynolds Number, Rayleigh Number and Prandtl No.
The code is running well but w- velocity contours(heating at bottom and cold at top) are coming only positive and negative alternatively and i am not getting rolls as expected. Can someone explain it.? Thanks in advance |
|
February 17, 2016, 03:18 |
|
#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,842
Rep Power: 73 |
Quote:
please, provide much more details about your code such as formulation, type of discretization, grid arrangement, values of the non-dimensional parameters, etc |
||
February 17, 2016, 05:07 |
|
#3 |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
I am implementing Pressure- velocity method, and using pressure poisson equation for divergence free flow. Ra=1800, Re=1.0, Pr=1. Grid is uniform in x and y while clustered with cos function in z direction(gravity). discreatisation is done utilizing fourth order Central differencing for diffusion terms, while third order Kawamura and K. Kuwahara upwinding for convective terms. thanks for reply.
|
|
February 17, 2016, 05:11 |
|
#4 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,842
Rep Power: 73 |
Quote:
if you use a second order discretization and a colocated arrangement, you could have experienced a decoupling-mode solution in the pressure equation. Could you post some figures of velocity and pressure fields? |
||
February 17, 2016, 05:21 |
|
#5 | |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
Quote:
Here are the figures encl : |
||
February 17, 2016, 05:42 |
|
#6 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,842
Rep Power: 73 |
it is a decoupling along the gravity axis, you can see the pressure field oscillating ... why don't you try using a staggered grid?
|
|
February 17, 2016, 05:52 |
|
#7 |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
Yes i am using collocated grid till now. Would you please suggest me some writeup on staggered grid implementation in view of this problem.
|
|
February 17, 2016, 06:01 |
|
#8 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,842
Rep Power: 73 |
Quote:
a second order discretization on staggered grid is a very old and well suited formulation, you can find that in any CFD textbook. For example, see the book of Peric & Ferziger |
||
February 17, 2016, 06:15 |
|
#9 |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
||
February 22, 2016, 00:17 |
|
#10 |
New Member
Madhup
Join Date: Feb 2016
Posts: 6
Rep Power: 10 |
Now i applied staggered grid, please see w-velocity profile , i can see rolls still. Will they apper after long time ?
|
|
February 22, 2016, 04:32 |
|
#11 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,842
Rep Power: 73 |
||
Tags |
finite difference method, fortran code, prandtl number, rayleigh-benard |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Rayleigh Benard convection in a bottom heated square cavity | arackal.rahul | Main CFD Forum | 2 | June 30, 2015 08:14 |
Rayleigh benard | afnene | FLUENT | 0 | June 12, 2015 11:29 |
conservative finite differences and finite volumes | Joachim | Main CFD Forum | 7 | January 23, 2014 16:32 |
Is CFD coding in finite element method a formidable job? | bearcat | Main CFD Forum | 0 | June 18, 2010 20:53 |
Finite differences | Zdravko Stojanovic | Main CFD Forum | 8 | March 24, 2001 22:31 |