Page 2 of 2

### Re: Variable boundary condition execution

Posted: 02 Oct 2020, 23:45
Dear Peter
How do I inactive dirichlet boundary condition in Elmer? I couldn't find it in Elmer manual

### Re: Variable boundary condition execution

Posted: 02 Oct 2020, 23:55
Boundary Condition 3
Target Boundaries(1) = 14
Name = "BoundaryCondition 3"
Temperature = 1023.001
External Pressure = Variable " Temperature"
Real MATC " exp(-7750/tx +12.79 - 1.41 * tx)*101300/760
Heat Flux = Variable " Velocity 3 "
Real MATC " -124700*24*0.01*tx "
End

When you set temperature to a constant, Temperature = 1023.001, it is that constant at the boundary condition.
External pressure is now function of a constant so it to is a constant, tx = T = constant, no variation in pressure

In mathematics, the Dirichlet (or first-type) boundary condition is a type of boundary condition, named after Peter Gustav Lejeune Dirichlet, When imposed on an ordinary or a partial differential equation, it specifies the values that a solution needs to take along the boundary of the domain.
The question of finding solutions to such equations is known as the Dirichlet problem. In applied sciences, a Dirichlet boundary condition may also be referred to as a fixed boundary condition.

### Re: Variable boundary condition execution

Posted: 03 Oct 2020, 00:26
Hello
So, how can I use the Dirichlet boundary condition variable? I need to set the heat flux variable of velocity 3. Temperature is a Dirichlet boundary condition, If I remove constant temperature, So, I can use Hat flux as a variable of velocity?

### Re: Variable boundary condition execution

Posted: 03 Oct 2020, 12:43
I believe you can do exact;y what you prescribed, but the boundary temperature and pressure will be constant.

### Re: Variable boundary condition execution

Posted: 03 Oct 2020, 15:03
Hello,
How can I make the pressure and heat flux boundary condition variables? I need to have a variable pressure and Hear flux in my modeling

### Re: Variable boundary condition execution

Posted: 05 Oct 2020, 11:20
Boundary Condition 3
Target Boundaries(1) = 14
Name = "BoundaryCondition 3"
Temperature = 1023.001 (Either Delete this)
External Pressure = Variable " Temperature" (or you have to pick something here that is not a constant)
Real MATC " exp(-7750/tx +12.79 - 1.41 * tx)*101300/760
Heat Flux = Variable " Velocity 3 "
Real MATC " -124700*24*0.01*tx "
End