CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > FLOW-3D

Surface roughness in Flow-3d

Register Blogs Community New Posts Updated Threads Search

Like Tree3Likes
  • 3 Post By Jorge D. Abad

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 23, 2008, 10:28
Default Surface roughness in Flow-3d
  #1
Marco
Guest
 
Posts: n/a
Dear experts :

In open channel, roughness coefficients are typically in one of two ways: (1)Chey's resistence coefficient, or(2)Manning's n. But in flow-3d, the roughness coefficients is use k (be expressed in unit of length).

So, flow-3d's roughness and open channel's roughness is different. I want to know how did I define the surface roughness if I simulated open channel flow. Did Manning's n necessary translate to roughness K by some equation or another methods?

May someone provide the opinion for me? Thanks your help!
  Reply With Quote

Old   December 23, 2008, 13:40
Default Re: Surface roughness in Flow-3d
  #2
Jorge D. Abad
Guest
 
Posts: n/a
Marco, I will suggest to take a look into Yen's book. The roughness (rough) in F3D is a Nikuradse type of roughness (ks), then, if you have values of Manning you can use the following equation:

ks[m]= (n[m^(1/6)]/0.0389)^6

where m is meters and n[m^(1/6)] is usually the values 0.030 (riprap) found in Open channel textbooks ==> ks=0.21039.

Remember Manning n above has units of m^(1/6). Further details read Yen's book.

Good luck

Jorge D. Abad

REFERENCE: Yen, Ben Chie (1991). "Channel flow resistance: centennial of Manning's formula:. Water Resources Publications.
zandi, loh561 and Hilbert.CFD like this.
  Reply With Quote

Old   December 23, 2008, 22:12
Default Re: Surface roughness in Flow-3d
  #3
Marco
Guest
 
Posts: n/a
Jorge D. Abad, very thanks your help!

So, I know manning value. And I use equation [ ks[m]= (n[m^(1/6)]/0.0389)^6 ] that I can get a ks value. Then input the surface roughness (ks) of surface properties in flow-3d. Did I solve roughness problem ?

Thanks you to provide the reference for me.
  Reply With Quote

Old   June 3, 2018, 03:15
Default mannin to Kikuradse
  #4
New Member
 
Hilbert Villafane
Join Date: May 2018
Posts: 2
Rep Power: 0
Hilbert.CFD is on a distinguished road
Quote:
Originally Posted by Marco
;93041
Jorge D. Abad, very thanks your help!

So, I know manning value. And I use equation [ ks[m]= (n[m^(1/6)]/0.0389)^6 ] that I can get a ks value. Then input the surface roughness (ks) of surface properties in flow-3d. Did I solve roughness problem ?

Thanks you to provide the reference for me.
Yes!
ks= (n/0.0389)^6 ....FORMULA
Ks: Nikuradse (m)
n:manning

file:///C:/Users/HP/Downloads/Marriott20M20201020AC26T2027.pdf
Hilbert.CFD is offline   Reply With Quote

Reply


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
Paraview fliter problem (surface flow) (segmentation fault) maysmech OpenFOAM 1 October 6, 2011 12:01
Laminar flow and roughness in fluent?? 1000sh FLUENT 0 April 16, 2010 15:42
mass flow rate on the Iso-clip surface & interior Sunil Gupta FLUENT 0 April 22, 2008 10:29
Looking for software for free surface flow Eric Jiang Main CFD Forum 12 December 18, 2007 00:39
effekt of surface roughness very small Ralf Schmidt FLUENT 0 December 7, 2007 06:46


All times are GMT -4. The time now is 11:55.