search

JanThorbecke / OpenSource

Code for geophysical 3D/2D Finite Difference modelling, Marchenko algorithms, 2D/3D x-w migration and utilities.
Other
139 stars 63 forks source link

gps per wavelength #18

Closed ImagLearning closed 4 weeks ago

ImagLearning commented 1 month ago

Hello Prof., this is actually not an issue, but more of a question. I noticed that whenever I run the "fdelmodc" code, it always uses 5 points per wavelength for the dispersion calculation. What can I do to make the code use 10 points instead?

JanThorbecke commented 1 month ago

You can decrease the spatial grid by a factor of 2 to get 5 points per wavelength. The dispersion calculation is carried out to check if the modeling will remain stable and without (visible) distortion. This stability demands to use at least 5 points per wavelength, but you can always use more points per wavelenght by decreasing dx=dz to smaller values. Due to this decrease in dx usually dt must also be adjusted to smaller values to remain stable and distortion free. See for example Table 1 in "Dispersion Analysis of Numerical Wave Propagation and Its Computational Consequences", Alain Sei and William Symes, Journal of Scientific Computing, Vok 10, No. 1, 1995

ImagLearning commented 1 month ago

Thank you, Prof.