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Old   October 15, 2011, 03:58
Default the problem about dimension
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bojiezhang
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hello everyFoamer:
I have two problems, and hope someone can help me,
1:when I use the function below:
Foam::cos( -omega*runTime.value())
the dimension of omega is[0,0,-1,0,0,0,0],
It can compile pretty well, but when caculating, the error comes as below:
ds not dimensionless
From function cos(const dimensionedScalar& ds)
2:when I assign the value as below:
mass[cellI] =A*omega*Foam::cos(-omega*runTime.value());
mass is volScalarField , and intialized as dimensionedScalar("zero", dimensionSet(0,1,-1,0,0,0,0), 0.0)
the dimension of A is [0,1,0,0,0,0,0],the dimension of omega is[0,0,-1,0,0,0,0],
when compiled , it shows "error":can not convert dimensioned<double> to double ;

what can I do , I really hope someone can give me some advice, thank you in advance!

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Old   October 15, 2011, 09:00
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Nima Sam
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1) define omega as dimless , because when u use the value() function, it only returns the value of run time not its dimension!

2) its not important whats the dimension of volScalarField is, when you use just on array of it! its a scalar with out dimension so the left side should be dimensionless too, but ur left side is not dimension less, its an strange combination of [0 0 1 0 0 0 0]* cos [0 0 -1 0 0 0 0] for compiler, so define A as dimless too then
congratulation both ur problem get solved
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Old   October 16, 2011, 00:22
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Quote:
Originally Posted by nimasam View Post
1) define omega as dimless , because when u use the value() function, it only returns the value of run time not its dimension!

2) its not important whats the dimension of volScalarField is, when you use just on array of it! its a scalar with out dimension so the left side should be dimensionless too, but ur left side is not dimension less, its an strange combination of [0 0 1 0 0 0 0]* cos [0 0 -1 0 0 0 0] for compiler, so define A as dimless too then
congratulation both ur problem get solved
Thank you for your reply, the problem is solved successfully by your idea!
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