Search found 8 matches

by mizuta
Tue Feb 01, 2011 8:34 am
Forum: ROMS Discussion
Topic: a possible improvement of the spline vertical viscosity
Replies: 2
Views: 1139

Re: a possible improvement of the spline vertical viscosity

Hi: Thank you for your valuable comments and document. of the velocity field to du/dz = sustr/Akv at the free surface. This is the only natural physical boundary condition, provided that (1) Akv remains finite at surface; and (2) the vertical profile of u (Ekman spiral or whatever) is adequately res...
by mizuta
Fri Jan 28, 2011 10:41 am
Forum: ROMS Discussion
Topic: a possible improvement of the spline vertical viscosity
Replies: 2
Views: 1139

a possible improvement of the spline vertical viscosity

Hi: I have a question about the spline interpolation used to get the stress by the vertical viscosity in step3d_uv.F. I guess that derivatives at the boundary (or alternatives) should be prescribed in the spline interpolation. What kind of the boundary condition is assumed in ROMS? It seems to me th...
by mizuta
Mon May 07, 2007 2:32 am
Forum: ROMS Problems
Topic: Negative passive tracer concentration
Replies: 5
Views: 3366

Just for your information, equations with a biharmonic term (which is used for mix4... option) e.g. p_t = -p_xxxx with p=delta(x) at t=0 do have negative solutions. Such features of the biharmonic term are quite different from those of the harmonic term (e.g. Pedlosky & Chapman 1993, JPO and related...
by mizuta
Fri Dec 02, 2005 3:04 am
Forum: ROMS Benchmarks
Topic: Benchmarks
Replies: 31
Views: 23095

This is not a direct answer but I wonder if this may be some hint for someone else. How does the commercial Intel Fortran compiler use CPUs? In my understanding one Xeon processor has two CPUs in it (is this correct?). In our HITACHI's machine which is an extreme example 1x1 tiling always gives the ...
by mizuta
Fri Nov 11, 2005 11:15 am
Forum: ROMS Benchmarks
Topic: Benchmarks
Replies: 31
Views: 23095

Thank you Mark. I learned another new thing. What is regarded as a bad example of programing in Fortran 77 is not so in Fortran 90. If I change the 2D kernel program of ROMS2x so that it uses older technique for work arrays, I may be able to get better performance in HITACHI's compiler. Let me try t...
by mizuta
Tue Nov 01, 2005 6:10 am
Forum: ROMS Benchmarks
Topic: Benchmarks
Replies: 31
Views: 23095

I just got back from other works. Thank you for your comments, Mark. I learned a lot of new things about ROMS 2x. I tried BENCHMARK1 instead of UPWELLING. I got results which are different from those for UPWELLING examples. For BENCHMARK1, ROMS2.1 is about 1.3 times faster than 1.8 on our HITACHI's ...
by mizuta
Tue Oct 18, 2005 12:36 pm
Forum: ROMS Benchmarks
Topic: Benchmarks
Replies: 31
Views: 23095

Thank you Mark. Now I have totally understood what you wrote on Nov 3, 2004. I changed "define ASSUMED_SHAPE" in globaldefs.h to "undef ASSUMED_SHAPE". However, ROMS slowed down more... I compared ROMS1.8 and 2.1 using UPWELLING example. Since cppdefs.h of this example is not exactly the same betwee...
by mizuta
Fri Oct 14, 2005 3:17 am
Forum: ROMS Benchmarks
Topic: Benchmarks
Replies: 31
Views: 23095

old compiler problem

Hi. I remember what Mark Hadfield wrote long time ago related with benchmark tests. ROMS2.x can be much slower than 1.8 on some "old" compilers due to implicit-shape of dummy arguments in 2.x. I am still encountering this problem and using 1.8 for my research. The compiler that I am using now (HITAC...