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[GAMBIT] Exponential en Bi-exponential grading

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Old   March 11, 2016, 14:42
Default Exponential en Bi-exponential grading
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Rob Vervoort
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Hello everyone,

I am experiencing some problems with grading in gambit.
I could not find a gambit manual since all the links to user manuals are offline.
I found another source that mentions the following (that obtained the formula from the gambit manual).

For exponential grading, gambit uses the following formula:

R = exp( (L/n) * (x-0.5))
or:
x = ( ln(R) / (L/n)) + 0.5

in which:

R = the ratio's of the cells.
L = the length of the edge
n = the number of intervals
and x is the ratio to specify in gambit

For example when having a edge with a length (L) of 15 with a cell ratio (R) of 2 and 4 intervals (n), thus a line with intervals with a length of 1-2-4-8, this results in a ratio of 0.6868 in gambit.

However when specifying this ratio in gambit and when looking at the intervals, the stretching ratio's of the cells are not equal to 2 (closer to 1.5).
A ratio around 0.776 in gambit is required to obtain the stretching ratio (R) = 2.

Could someone tell me how the exponential and bi-exponential grading works? In grid I want to apply stretching ratio's of 1.1 over the entire domain.

Thank you in advance,
Rob





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Old   March 14, 2016, 02:27
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