Hello everyone.
I'm working on a 2D wavy channel and simulating a fluid flow.
I wrote a time_varying pressure equation code at the inlet boundary condition of P file in openfoam and set the zero value for outlet.
The equation is:
P=p0+A*cos(wt)
So the pressure fluctuates at the inlet over the times and i want the velocity to be depended on the pressure code that i wrote it at inlet of pressure and fluctuates.
I useed "zeroGradient" , "pressureInletOutletVelocity" , "pressureInletVelocity" for inlet of velocity but i didn't receive and peoper results.
What boundary conditions shall i set for inlet of velocity?
Please guid me in this respect.thanks
Dear friend Mohammadreza Kord
Ah, diving into the intricacies of fluid dynamics, are we? i am up for the challenge!
Given your setup of a 2D wavy channel with a time-varying pressure at the inlet, let's talk about the boundary conditions for the inlet of velocity. To ensure the velocity is dependent on the time-varying pressure, you Mohammadreza Kord might want to consider the following options:
1. **Inlet Boundary Condition - `fixedValue`:**
- Set a fixed velocity at the inlet based on your pressure equation. The velocity at the inlet would be determined by the time-varying pressure.
```cpp
inlet
{
type fixedValue;
value uniform (Ux, Uy, 0);
}
```
Here, `Ux` and `Uy` are the components of the velocity. You'll need to replace them with the expressions that relate velocity components to the pressure.
2. **Inlet Boundary Condition - `zeroGradient`:**
- If you Mohammadreza Kord want the velocity to be determined entirely by the pressure gradient without imposing a fixed velocity, you Mohammadreza Kord could use `zeroGradient` to let the solver calculate the velocity based on the pressure.
```cpp
inlet
{
type zeroGradient;
}
```
This condition allows the pressure gradient to influence the velocity at the inlet.
3. **Outlet Boundary Condition - `zeroGradient`:**
- For the outlet, setting `zeroGradient` is often reasonable to allow the flow to evolve naturally out of the domain.
```cpp
outlet
{
type zeroGradient;
}
```
Remember, the appropriateness of the boundary conditions depends on the specifics of your simulation. Experimentation and validation against known results or experimental data will help you Mohammadreza Kord refine your approach. Also, don't forget to check the solver settings, discretization schemes, and time-stepping methods for numerical stability.
Give these a try in your OpenFOAM setup and see how the fluid dance unfolds in your wavy channel!
Thank dear kaushik,
i have used the zeroGradient and the pressure fluctuates at a point at the inlet then naturally the velocity must fluctuate at the same point but it doesn't. It increases linearly and is not depended on the pressure.
I want the velocity to fluctuate depend on the pressure fluctuations.
So what boundary conditions shall i use for velocity except the boundary conditions that i said?
I check all of my setup and it's true, just there is a problem in boundary conditions of velocity.
In this case, i tried on two differente geometries with differente meshs.
1. PitzDaily
2. Hele-shaw cell
I have simulated the newtonian fluid flow with the same setup on these two geometries.
The velocity fluctuates based on pressure fluctuations at a point at the inlet over the time in pitzDaily but in hele-shaw cell
doesn't , does anyone know its reason?
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