What I want to get is a time series of the free surface position, something like a vector as a function of time (eta(t)), basically to see how the inner free surface decays in time. We have experimental data in our lab for this very case, a wave gauge placed at the very center of the cylinder, and I wanted to validate this simulation (part of an introductory level course on cfd).
Ideally I’d be interested in having the entire free surface location for each timestep, like a cloud of points for each instant (z(x,y,t)), but I assume this might be computational costly so I am focusing on specific locations (such as the center of the cylinder) that I can validate. The elevation outside the OWC, at least now, is not so important (I will probably have to check the domain size, but this is in the future). Any approach based on the frames is not the ideal due to the small number of frames or large size of the files I’d get. The decay period is close to 0.5 s, therefore I need a ‘sampling’ frequency of at least 10 Hz to minimally capture the cicle properly. Furthermore, I need something I can handle externally, like in matlab, so I can treat the data. That’s why I am focusing on some of the Result Control tools, because I can download the csv file corresponding to it.
Besides this attempt of using the alpha, which is not working very well until now, I thought of using what I assume to be the hydrostatic pressure (p_rgh) or the vertical velocity (Uz) in the points, but neither is working well to me yet, the former because p_rgh is larger in shallower points, which doesn’t make sense to me, and the later because the integration of the signal is the ideal approach.