Learning Forum

[Kauê Castro]

Greetings, so while trying to simulate my problem, I'm having a little trouble when it comes to initializing it. You see, the standard Initialization attributes the same value for all elements, however, my inlet has a initial mean velocity of about 10,5 m/s and I have another inlet boundary which has a step function to be intialized later on. If I initialize using a absolute velocity of 10,5 m/s, the boundary with the step function works incorrectly, but if I initialize with 0 m/s, the main velocity inlet gives out a velocity of 1,5 m/s instead of 10,5. 

the oscilating inlet is in the upper end of the boundary. For that, I thought that a possible solution mas to make a different initialization value for each boundary, but there is only the "Standard Initialization" and "Hybrid Initialization" options. 

[Rob]

Hybrid may give you a better starting point. Otherwise have a look at "Patch" and (Adaption) Registers. 

[Kauê Castro]

Hey Rob, do you know how I can make a pressure oscilation without inserting mass? Im using a pressure-inlet, in spite of that, it's still inserting mass: 

 

[Rob]

A pressure inlet will add mass if it's at a higher value than the fluid zone. If you're trying to mimic the surface vibrating or a piston you'll need to use moving mesh. Although momentum source terms might be another option. 

[Kauê Castro]

So, I would need to make a wall of some sorts that moves? Can I make just a portion of fluid move?

[Rob]

Source terms can be used to make fluid move without adding mass, but that mass has to come from somewhere so it's not always suitable: it's good for fans etc not so much vibrating surfaces. If it's a vibrating surface you'll want moving mesh.