Hey all,
I am trying to run a flow simulation on some new rudder designs. I basically want to figure out some lift and drag forces. To do this I was looking at forces in the x and y direction. Attached is the solidworks file. When I run the simulation at a 7 degree angle of attack (4m/s in x direction, 0.49m/s in the y direction) the x component of force (the drag part) is indicating that it is negative, implying that the rudder has negative drag. I double checked and am not mixing up any signs, and it appears to have significant lift (800N) or so. I am a student doing an independent study and trying to learn the software as well, so any help would be greatly appreciated.
A secondary question: I have been struggling out how to make my model a bit more complex. The current simulation just restricts my fluid range to where the water line is (343mm down from the top of the rudder). It would be much better if I could have two fluids, air above that line and water below, as i can experiment with different mounting solutions for the rudder head which connect just above the water line.
Best,
Josh
after running your analysis, i'm going to have to think a bit about the force direction at the angle of attack. my first thought is that it could be because you don't have a "closed surface" in flow which would cause issues with force output (or any integral value). my second thought is mesh density and size of the computational domain. i would try running your rudder as if it is completely submerged and make the comp domain larger and use solution adaptive meshing to see if that helps. when you're outputting the force, make sure you include all of the faces in a single goal or surface parameter.
regarding your second question, that can't be done with flow simulation. you need something that can handle free surface to do that analysis. i can't really think of a good workaround for it unless you put a thin barrier at the surface and consider them separate regions that don't interact. but then you have to ask yourself what you want to learn by learning about what is above the water line.