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-   -   TimeVaryingUniformFixedValue (http://www.cfd-online.com/Forums/openfoam-solving/59162-timevaryinguniformfixedvalue.html)

holger_marschall February 7, 2008 11:07

Dear Foamers, I tried to im
 
Dear Foamers,

I tried to implement a TimeVaryingUniformFixedValue b.c. for a velocity inlet:

inlet.dat:
~~~~~~~~~~
N
(
t0 (v1 v2 v3)
t1 (v1 v2 v3)
t2 (v1 v2 v3)
....
tN (v1 v2 v3)
)

in 0/U:
~~~~~~~
INLET
{
type timeVaryingUniformFixedValue;
timeDataFileName "inlet.dat";
}

But the error message I got when I started the simulation run:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

--> FOAM FATAL IO ERROR : wrong token type - expected Scalar found on line 3 the punctuation token '('

file: inlet.dat at line 3.

From function operator>>(Istream&, Scalar&)
in file lnInclude/Scalar.C at line 85.

FOAM exiting

Can anybody tell me what I did wrong? Did I use the right syntax in inlet.dat?

Holger

philippose February 7, 2008 13:54

Hello Holger, Good Evening!
 
Hello Holger,

Good Evening!

The TimeVaryingUniformFixedValue boundary condition does not accept vectors in the data file... it can only handle scalars.

However, to use this boundary condition in the case of a vector (as in your case, velocity), all you need to do, is to specify the magnitude of the vector.

The boundary condition automatically calculates the surface normal of each face on the patch(es) you have specified, and applies the magnitude you have given in the data file along the direction of the surface normal.

The sign convention is such that, if you give a positive number for the magnitude in the time data file, the velocity will be pointed into your domain (and as mentioned, in a direction normal to each face on each specified patch).

Enjoy and have a nice day!

Philippose

holger_marschall February 7, 2008 14:12

Hello, thanks a lot! It wor
 
Hello,

thanks a lot! It works now http://www.cfd-online.com/OpenFOAM_D...part/happy.gif

P.S.: I searched even on google for that information. Don't know if somebody has access to http://www.durun.cn/?p=320 and could change the wrong thread there.

best regards,
Holger

heavy_user December 17, 2009 13:25

Hi There,

I am trying to have a time dependent inlet-condition.
(I want the velocity to raise, since pressure corretion messes up when i start up with the high velocity).

But I get a message with which i cant deal.


.....
Create mesh for time = 0


Reading g
Reading thermophysical properties

Reading field T

Reading field p

Reading field U

Expected a '(' while reading VectorSpace<Form, Cmpt, nCmpt>, found on line 27 the doubleScalar 100000

file: /home/OpenFOAM/OpenFOAM-1.6/OWN/jetflame/V4/0/U::value at line 27.

From function Istream::readBegin(const char*)
in file db/IOstreams/IOstreams/Istream.C at line 87.

FOAM exiting
............
the .dat file:

(
( 0.00005 ( 0 0 0.1000 ) )
( 0.00010 ( 0 0 0.2058 ) )
( 0.00015 ( 0 0 0.3116 ) )
( 0.00020 ( 0 0 0.4174 ) )
( 0.00025 ( 0 0 0.5232 ) )
( 0.00030 ( 0 0 0.6290 ) )
( 0.00035 ( 0 0 0.7348 ) )
( 0.00040 ( 0 0 0.8406 ) )
( 0.00045 ( 0 0 0.9464 ) )
( 0.00050 ( 0 0 1.0522 ) )
( 0.00055 ( 0 0 1.1580 ) )
( 0.00060 ( 0 0 1.2638 ) )
( 0.00065 ( 0 0 1.3696 ) )
( 0.00070 ( 0 0 1.4754 ) )
( 0.00075 ( 0 0 1.5812 ) )
( 0.00080 ( 0 0 1.6870 ) )
( 0.00085 ( 0 0 1.7928 ) )
( 0.00090 ( 0 0 1.8986 ) )
( 0.00095 ( 0 0 2.0044 ) )
( 0.00100 ( 0 0 2.1102 ) )
( 0.00105 ( 0 0 2.2160 ) )
( 0.00110 ( 0 0 2.3218 ) )
( 0.00115 ( 0 0 2.4276 ) )
( 0.00120 ( 0 0 2.5334 ) )
( 0.00125 ( 0 0 2.6392 ) )
( 0.00130 ( 0 0 2.7450 ) )
( 0.00135 ( 0 0 2.8508 ) ) // line 27 (stating from line 0)
( 0.00140 ( 0 0 2.9566 ) )
( 0.00145 ( 0 0 3.0624 ) )
( 0.00150 ( 0 0 3.1682 ) )
( 0.00155 ( 0 0 3.2740 ) )
( 0.00160 ( 0 0 3.3798 ) )
( 0.00165 ( 0 0 3.4856 ) )
( 0.00170 ( 0 0 3.5914 ) )
( 0.00175 ( 0 0 3.6972 ) )
( 0.00180 ( 0 0 3.8030 ) )
( 0.00185 ( 0 0 3.9088 ) )
( 0.00190 ( 0 0 4.0146 ) )
( 0.00195 ( 0 0 4.1204 ) )
...........

I cant find a missing "(" and there is no value "100000" -> :confused:
Any Ideas????


regards

Islam ElQatary August 10, 2013 14:47

Quote:

Originally Posted by philippose (Post 187050)
Hello Holger,

Good Evening!

The TimeVaryingUniformFixedValue boundary condition does not accept vectors in the data file... it can only handle scalars.

However, to use this boundary condition in the case of a vector (as in your case, velocity), all you need to do, is to specify the magnitude of the vector.

The boundary condition automatically calculates the surface normal of each face on the patch(es) you have specified, and applies the magnitude you have given in the data file along the direction of the surface normal.

The sign convention is such that, if you give a positive number for the magnitude in the time data file, the velocity will be pointed into your domain (and as mentioned, in a direction normal to each face on each specified patch).

Enjoy and have a nice day!

Philippose

Hello
Does anyone know how to change the inlet speed direction with time?
like if I want to change the angle of attack on the airfoil with time
thanks


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