Outflow: add option for computing the flow of unbounded matter

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Issue #1535 closed
David Radice created an issue

I created a small patch for the Outflow thorn to allow one to optionally compute the flux of matter having "eninf := - u_t - 1" larger than a given threshold, so as to measure the amount of "unbound" (*) matter ejected from the system.

(*) Obviously this really makes sense only for a stationary spacetime


Comments (7)

  1. Roland Haas
    • changed status to open
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    The patch is mostly fine. However it removes the magic value "-1" from the threshold parameter description without removing the magic value handling code (look for "is set to -1, ignoring."). I am in principle fine removing the magic value, however in case someone actually used this, it would be better to keep the magic value in param.ccl but 1. document in param.ccl that this only works with w_lorentz 2. moves the code that skips int the threshold_on_w_lorentz branch is the if statement or if we are sure that u_t > -1 for all "valid" points anyway we can also just re-add the magic value to param.ccl.

  2. David Radice reporter
    • removed comment

    Yes I missed the part of the code explicitly checking for '-1' as a threshold.

    I would remove the magic value completely as it seems to me to be duplicating the num_thresholds parameter. This would not break old parfiles, because, in the worst case, it would only result in more columns being added to the output file.

  3. Roland Haas
    • changed status to open
    • removed comment

    Using "-1" lets a user disable individual thresholds (eg the 10 out of 14) while num_thresholds can only disable the topmost ones. For the thresholds it should not really matter what is there and since the patch will change output in files anyway, it may not matter. Computing the thresholds is cheap so it is not like eg not being able to disable a particular apparent horizon finder in AHFinderDirect.

    So, please apply as long as the code checking for '-1' is removed as well.

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