AnsweredAssumed Answered

Ventilation diffuser design, and flow simulation questions

Question asked by Samuel Nilsson on May 21, 2014
Latest reply on Jul 16, 2014 by Jared Conway



I have been doing some flow simulations but sometimes they sometimes seem strange and non realistic. Maybe I have done something wrong or the program is i bit wierd. Small changes can make huge differences. Sometines the fluid stops as it hits a surface.


I also get many error messages like "There is no fluid volume in the project. Please check geometry or boundary conditions." Sometimes I can fix this by increasing the size of the computional domain, making sure there is no small hole or fixing boundary conditions. Sometimes SW is very stubborn and does not cooperate. (At least how I feel).


I found it easier to do simulation when only doing it on a part. I could not do it on an assembly.


Another thing I have noticed is that my settings, like preasure, temperature or volume flow doesn´t affect the air flow in the room.


I am doing a project constructing a ventilation diffuser that is placed on a wall near the celing. I want the air to go across the room near the roof before it sinks down. In many cases the "fresh air" turns to the side towards the wall and drops down to the floor. I wonder why? Any ideas on ventilation diffuser designs (with a connection box) for an airflow that reaches the opposite wall and then spreads out while going down, mixing with the "usead air" and finally returning to an outlet on the same wall as the inlet?





halvklotsdon med hål.png

This flow seen above is quite good I think but I want to achive it by using an inlet on a connection box outside of the room. That inlet is facing upwards so the air has to do a 90 °

turn in the box.




cfd tilluftsdon 20 maj.png

This is what the flow usually looks like using a connection box.







A simle version of a  connection box. I have also tried with a front of perforated sheet.