Minimize reflections off lateral boundaries
Before I dive into this rabbit hole, I wanted to see if anyone has tried this, and succeeded, or if it's even possible. I'm working on a numerical wave tank, in which a rigid object is to be placed about 1/2 way downstream of a piston wave maker. I've run tests without the object and compared the wave elevations with experimental data and it's near perfect. So my generation, settings, etc. all seem good to go!
After placing the object in the domain, I'm getting reflections off the object, which is expected. However, those reflections are now reflecting off the lateral walls and pollute the wave field making difficult to compare with experimental data. To make matters worse, they eventually hit my wave maker and get amplified to create a standing wave field that was nonexistent in the experiment. The domain length is already quite long, so I can only go so wide before I run out of memory.
I'm wondering if I can modify the lateral boundaries so they act like an outflow boundary? Maybe some type of absorption? The waves propagate down the basin at a normal incident angle. In theory, the only waves that would "exit" the domain would be those that are not parallel to the lateral boundary. If I can get this to work, it would not only save a significant amount of computation time, it will also clean up my wave field. This seems like a common challenge, but I haven't read much about this treatment in the docs.