# Typo in User Guide - Please Check

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June 26, 2009, 18:42
Typo in User Guide - Please Check
#1
Senior Member

Join Date: Mar 2009
Posts: 248
Rep Power: 18
Dear Developers

Sorry for posting this message here as there is no separate section for reporting such typos.

In the 2nd chapter on page U - 40 under the section 2.1.8.1 following is written:

Quote:
 Open the field files for and (0/k and 0/epsilon) and examine the boundary conditions. For a wall boundary condition, is assigned a zeroGradient boundary condition and a fixedValue 0 boundary condition is assigned to . How are the initial values of and arrived at? Positive, non-zero initial values for and must be given to avoid division by 0 in the solution algorithm.
As written here k is to be assigned fixedValue on the walls but this is not correct. The tutorial uses zeroGradient and also the wall functions used in High-Re turbulene models have in-built check to make sure that the boundary conditions on walls are zeroGradient.

Best Regards
jaswi

June 29, 2009, 14:33
#2
Senior Member

Ahmed
Join Date: Mar 2009
Location: NY
Posts: 251
Rep Power: 18
and a fixedValue 0 boundary condition is assigned to
Quote:
 Originally Posted by jaswi Dear Developers Sorry for posting this message here as there is no separate section for reporting such typos. In the 2nd chapter on page U - 40 under the section 2.1.8.1 following is written: As written here k is to be assigned fixedValue on the walls but this is not correct. The tutorial uses zeroGradient and also the wall functions used in High-Re turbulene models have in-built check to make sure that the boundary conditions on walls are zeroGradient. Best Regards jaswi

( and a fixedValue 0 boundary condition is assigned to ,) no slip boundary condition, velocity is zero at the wall hence k is 0

 June 29, 2009, 17:03 #3 Senior Member   Join Date: Mar 2009 Posts: 248 Rep Power: 18 Hi Ahmed I did not understand your post. By k is 0, do you mean that k being set to fixedValue is correct ? Please comment on this as after reading your post I tried to set k as fixedValue and value 0 but I get error that at wall k should be zerogradient. The message comes from this section of wallFunctionsI.H: forAll(patches, patchi) { const fvPatch& curPatch = patches[patchi]; if (isType(curPatch)) { # include "checkPatchFieldTypes.H" ........ ......... where in checkPatchFieldTypes.H it is checked for the patch to be zeroGradient else raise FatalError. This is what it reads: if (!isType(k_.bounda ryField()[patchi])) 00002 { 00003 FatalErrorIn("wall-function evaluation") 00004 << k_.boundaryField()[patchi].type() 00005 << " is the wrong k patchField type for wall-functions on patch " 00006 << curPatch.name() << nl 00007 << " should be zeroGradient" 00008 << exit(FatalError); 00009 } 00010 00011 if (!isType(epsilon_. boundaryField()[patchi])) 00012 { 00013 FatalErrorIn("wall-function evaluation") 00014 << epsilon_.boundaryField()[patchi].type() 00015 << " is the wrong epsilon patchField type for wall-functions on patch " 00016 << curPatch.name() << nl 00017 << " should be zeroGradient" 00018 << exit(FatalError); 00019 } Any comments are appreciated BR jaswi