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May 10, 2012, 00:23 |
Boundary conditions/solver
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#1 |
New Member
Christiane
Join Date: May 2012
Posts: 8
Rep Power: 13 |
Hi!
I have to simulate a screw extruder. I have set up the geometry - I have an inlet and an outlet needle. I have the inlet as one part, the screw fluid as one part and the needle part. I meshed within ANSYS workbench. Named the inlet and outlet as well as the screw wall. I set up: Using laminar flow, defining a new fluid (PCL) with values I found in the literature. For the cell zone condition I put fluid everywhere. For the screw fluid body I also tick frame rotation with rotation around - y axis with a certain speed. Boundary conditions: Inlet-pressure 7e5 Pa, outlet-pressure 0 Pa gauge pressure, screw_wall is rotating around - y axis with the same speed as the frame rotation. Solver is Presto and second order upwind momentum. Monitors is the convergence turned off. Then I initialize. And then run until stable around 4000 iteration steps. PROBLEMS that I have: 1) it is stable, but in the 10^3 range rather than 10^-4 range. 2) I tried standard/ second as well as standard/first, but the problems remains. 3) I didn't rotate the frame. And the same thing happens (stabilized at around 10^3) 4) If I make the whole extruder out of one part, then I get stabilizing in the 10^-4 to 10^-16 range for standard/second. If I use presto - I get still 10^3 and oscillating like crazy. That brought me to the thought, that something must be wrong with my parts and their connection maybe. Please give me some suggestions what I can try out next. Christiane |
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