Assigning constants values to initial conditions

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orestis
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Joined: 13 Jul 2022, 16:07
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Assigning constants values to initial conditions

Post by orestis »

Good morning to all,

I have a case.sif input file that uses another file to include some constants like:

Constants
Gravity(4) = 0 -1 0 9.82
Unit Charge = 1.6021766e-19
.
.
.
!--------------------------------
include myInputParams.dat
!--------------------------------
END

... where the myInputParams.dat file contains the following lines:
nComp(2) = Real 4.0 3.0248
thCComp(2) = Real 0.2004 0.1187
vel2 = Real 10.0

(the array-like parameters are used for some UDF I have created ...)

I want to be able to assign the vel2 parameter value inside the Initial Condition section for e.g. Velocity 2:

Initial Condition 1
Name = "InitialCondition 1"
Velocity 2 = vel2 (or something equivalent)
End

Is this possible somehow ? (I know that I can create another .dat file and include it in the Initial Condition 1 section as with the Constants section but I want to avoid that)

Thanks very much in advance
raback
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Re: Assigning constants values to initial conditions

Post by raback »

Hi,

Do like this:

Code: Select all

$vel2=10.0
...
Velocity 2 = $vel2
So here the "vel2" never becomes a legit keyword inside Elmer. It is just used when reading the sif file and interpreted by the built-in matc parser. The "$" tells the code that this one should be dealt with matc. It is noteworrthy that matc has two operating modes. This "$" used when reading the file, and "MATC" when evaluating expressions in each nodal point.

So you could also have the following present a parabolic velocity profile in x \in [0,1].

Code: Select all

Velocity 2 = Variable "coordinate 1"
  Real MATC "4*vel2*tx*(1-tx)"
-Peter
orestis
Posts: 2
Joined: 13 Jul 2022, 16:07
Antispam: Yes

Re: Assigning constants values to initial conditions

Post by orestis »

Hi Peter,

thanks very much for the information.
That worked like a charm !
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