I want to create pathlines from a dataset which I already uploaded here regarding a different topic.
State file: pathlines_try.pvsm (1013.8 KB)
Dataset: data.zip - Google Drive
Version: 5.13.0
The data represents flow in a blood vessel. I am interested in visualizing the paths which (zero mass) particles/parts of the fluid follow.
When playing back the time steps, the number of particles fluctuates heavily. This does not make sense to me since I set „Mask Points“ to 100 (ratio) and the number of points from the Threshold filter varies very little over the whole time. Hence, the number of particles (every 100th) should also remain within a small margin, right? Please see the pictures below. This is even more visible in the Statistics Inspector window. Is this the expected behavior or did I get something wrong?
I have trouble finding the right settings for the „Max Step Distance“ of the pathlines. It seems like increasing the value lengthens the pathlines as expected but they are always only straight lines. I suppose this has something to do with particle ID’s? Maybe new points are selected every time step and therefore no reasonable traces can be found for them? (Maybe it is similar to this case?: "Temporal Particles To Path-lines" and "Temporal Interpolation" filters...do they require particles to be defined for every time step?) I am not sure about this and probably do not completely understand how the filter works. How can I create pathlines correctly?
thank you very much for the explanation! And thank you even more for providing a state file with the solution and all the right settings, you helped me a lot!
I have one more question about your input for the Particle Tracer filter:
You used a calculator filter as the input where you divided the vectors of the velocity field by 10. I assume this decreases the magnitude of each vector to 1/10th of the original value, right?
When changing this parameter, I see that the pathlines become longer and more “cornered” when approaching the original vector’s values and vice versa. So is this only a trick for a more beautiful visualization? By doing so, will the pathlines still show the real behavior of the fluid that we measured? I am not sure if the particles still represent real parts of the fluid from our measurement anymore, I mean this cannot be the case, right? But the pathlines look plausible and since the dataset consists only of velocities, pathlines are a theoretical concept anyway.
So is this only a trick for a more beautiful visualization?
Yes, with the original vector, the particles move “too fast” and get stuck on the edges too soon to see anything interesting imo
By doing so, will the pathlines still show the real behavior of the fluid that we measured?
I’m afraid this is for you to say
I am not sure if the particles still represent real parts of the fluid from our measurement anymore, I mean this cannot be the case, right?
The particle tracer is just moving particles around using a velocity vector. The “true” pathlines should be without the factor, but may be hard to exploit.
