Search found 4827 matches

by Jirka
Sat Mar 16, 2002 5:43 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Tips for attaining steady state solutions
Replies: 1
Views: 3149

John, The option to find steady-state solution to specified boundary conditions (activated by switching off "Water Flow" check box) is not the most robust ones. It succeds mainly for fully saturated conditions, and for unsaturated conditions only when the soil hydraulic parameters are not extremely ...
by Jirka
Sat Mar 16, 2002 5:41 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Mass Balance Error
Replies: 1
Views: 3375

Preecha, Since HYDRUS uses mass conservative solution of the Richards equation, the mass balances are in general very small. If you obtain large mass balance errors, it should be a flag that your discretization is not sufficiently fine and you should start from the beginning with finer discretizatio...
by Jirka
Sat Mar 16, 2002 5:40 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Variable head boundaries / field capacity concept
Replies: 1
Views: 2818

Dear Hector, The natural boundary conditions are obviously much more complex and dynamic than those in version 2.0 of HYDRUS-2D. I have been struggling last year in developing more complex boundary conditions for the next version. The dynamic interface between the stream (variable head BC) and dry s...
by Jirka
Sat Mar 16, 2002 5:38 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Units
Replies: 1
Views: 2937

Defne, One needs to use the same units throughout the input, i.e. time and lenght units must be everywhere the same. Also the concentration units should preferable use the same units as when designing transport domain, etc. But for concentration units it is necessary to keep this convention. Since c...
by Jirka
Sat Mar 16, 2002 5:36 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Variable head boundaries REVISITED
Replies: 3
Views: 3963

Yes, I'm implementing this dynamic change in BC.

J.
by Jirka
Sat Mar 16, 2002 5:35 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Variable head boundaries REVISITED
Replies: 3
Views: 3963

Dear Hector, The natural boundary conditions are obviously much more complex and dynamic than those in version 2.0 of HYDRUS-2D. I have been struggling last year in developing more complex boundary conditions for the next version. The dynamic interface between the stream (variable head BC) and dry s...
by Jirka
Sat Mar 16, 2002 5:33 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Snowmelt
Replies: 2
Views: 3449

Catherine, HYDRUS codes at this moment do not deal with snow-melt issues at all. You need to specify fluxes at the soil surface that can actually infiltrate into the soil profile. Snow will not do. You can use something as the degree day concept and calculate in advance when snow accumulates at the ...
by Jirka
Sat Mar 16, 2002 5:26 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Assignement of Anisotropy ratio & angle
Replies: 1
Views: 3129

Hector, As usual you have exactly pin-pointed where we could improve the graphical interface. At this moment one needs to make a domain selection and then specify each anisotrophy parameter independently. If I understand correctly you suggest that we should allow users an option to select transport ...
by Jirka
Sat Mar 16, 2002 5:20 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Inverse Solution
Replies: 1
Views: 2758

George,

This is exactly what the program was written for: to analyze water flow in soils. HYDRUS can solve both direct as well as inverse (i.e. calibration) problem.

Good luck in analyzing your data. Let me know if you have any more specific questions.

Jirka Simunek
by Jirka
Sat Mar 16, 2002 5:17 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Mass transfer coef alpha in physical nonequlibrium
Replies: 1
Views: 5104

Markus, You can see best how the mass transfer coefficient is implemented into the mobile-immobile physical nonequilibrium model directly from the governing equations. This would be equation 3.19 (numerical implementation is discussed in Section 6.3) in the HYDRUS-1D manual and equation 3.18 (and nu...
by Jirka
Sat Mar 16, 2002 5:15 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Number of subregions
Replies: 1
Views: 2747

Uwe, a) The HYDRUS-2D allows only 10 subregions in one simulation run. b) Root distribution parameters. This command (Options->Parameters for Root Distribution) in the Boundary module was not part of the version 2.0 of HYDRUS-2D. I added it only last year when I was working with Jasper Vrugt and Jan...
by Jirka
Sat Mar 16, 2002 5:12 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Hydraulic total head
Replies: 1
Views: 2725

Dear IJsbrand, There are no restrictions on displaying results of existing HYDRUS-2d projects with a demo version. Similarly as you can see all the text examples (installed with the HYDRUS-2D code) , your colleagues should be able to view the projects created by you. You just need to send them the p...
by Jirka
Sat Mar 16, 2002 5:11 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Detection of critical gradients in a domain
Replies: 1
Views: 2799

Hector, Thanks for another suggestion. I do not think that the way material properties are assigned (either to elements or nodes) has any effect on how the gradients are calculated. It has effect only on how the velocities are calculated since then one has to consider conductivities (and they depend...
by Jirka
Sat Mar 16, 2002 5:04 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Variable boundary head
Replies: 1
Views: 3179

Dear Mo'ayyad, You should specify the variable boundary head from z=1.0 to z=5.5. However, when the water level drops, the code will prescribe fixed negative pressure above the water level. You need to split the problem into two. First run one BC (5.5m), then copy the input, import result, and resta...
by Jirka
Sat Mar 16, 2002 5:00 pm
Forum: Hydrus 2D (old version 1996 - 2005)
Topic: Hydraulic Potential Output
Replies: 1
Views: 2852

Dear Hector, I see that we are proceeding in the right direction. I got similar suggestion, i.e., to print in addition to pressure heads also total heads, earlier this year and implemented it in quite similar way as you suggested. I have a version of the HYDRUS2 code that prints out a new output fil...