Search found 5304 matches

by Jirka
Sat Sep 18, 2021 8:38 pm
Forum: Hydrus 1D
Topic: Water Content Post-processing
Replies: 1
Views: 45

Re: Water Content Post-processing

Quote “So what wrong with this problems?” Problem seems to be your basic understanding of soil physics. A zero pressure head BC does not mean a zero flux BC, it means a zero pressure head at the boundary. Note that the zero pressure head corresponds to full saturation (see the retention curve). If y...
by Jirka
Wed Sep 15, 2021 9:20 pm
Forum: Hydrus 1D
Topic: Two questions on inverse modeling and one on IC
Replies: 1
Views: 46

Re: Two questions on inverse modeling and one on IC

Q1: If you use type 12 (for pressure heads) or 13 (for water contents), then it should be -40, e.g., -40 0.35 13 iPrint Weight If you use type 1 (for pressure heads) or 2 (for water contents), then you should give the observation node number, e.g., Time 0.35 2 iObs Weight You should be able to see i...
by Jirka
Tue Sep 14, 2021 10:42 pm
Forum: Hydrus 1D
Topic: Runoff generation concern
Replies: 1
Views: 74

Re: Runoff generation concern

I do not see the graph very well. Anyway, the infiltration capacity is not equal to Ks. Because of the capillary forces, it is actually much larger when the soil is initially dry. Infiltration capacity is equal to Ks only at large times, when capillarity dissipates and only gravity drives infiltrati...
by Jirka
Tue Sep 14, 2021 4:26 pm
Forum: Hydrus 1D
Topic: run hydrus outside GUI.
Replies: 1
Views: 51

Re: run hydrus outside GUI.

I’m sure that you will figure out yourself where one sets time-variable BC in the HYDRUS-1D GUI. This discussion forum is not intended for such trivial questions. J.
by Jirka
Mon Sep 13, 2021 1:31 pm
Forum: Hydrus 1D
Topic: Change the Legend Label Name
Replies: 4
Views: 104

Re: Change the Legend Label Name

I have hardcoded the legend, i.e., T0-Tn for print times, N1-Nn for observation nodes, M1-Mn for material numbers, and PotTop, PotRoot, actTop, ActRoot, and actBot for various potential and actual surface fluxes, transpirations, and bottom flux, etc. These texts cannot be changed. You can obviously ...
by Jirka
Fri Sep 10, 2021 5:19 pm
Forum: HYDRUS (2D/3D)
Topic: very small scale root solute uptake
Replies: 3
Views: 133

Re: very small scale root solute uptake

You can actually use the time-variable BC, but if you want to have no solute flux across this BC, you need to ask the code to treat the boundary as an atmospheric boundary (Special BC Options). Anway, transpiration is completely independent of the atmospheric BC. J.
by Jirka
Tue Sep 07, 2021 7:39 am
Forum: Hydrus 1D
Topic: transient flow, headless / batch mode
Replies: 1
Views: 89

Re: transient flow, headless / batch mode

There is the technical manual, which describes all of this, and you should consult it before posting questions in the discussion forum. It is in the Atmosph.in file, which does not seem so difficult to find between the four input files. J.
by Jirka
Sat Sep 04, 2021 2:28 pm
Forum: HYDRUS (2D/3D)
Topic: very small scale root solute uptake
Replies: 3
Views: 133

Re: very small scale root solute uptake

The first approach using a BC on a circle: Depending on the BC that you apply on the circle, e.g., either atmospheric or time-variable flux BC, there is either a zero solute flux (no solute outflow across the atmospheric BC) or solute flux equal to qc, where q is the boundary water flux and c is the...
by Jirka
Fri Aug 27, 2021 9:48 am
Forum: HYDRUS (2D/3D)
Topic: Setting appropriate BCs
Replies: 5
Views: 168

Re: Setting appropriate BCs

I have nothing more to say. The BC at the plane (axis) of symmetry should be zero flow. J.
by Jirka
Fri Aug 27, 2021 9:44 am
Forum: Hydrus 1D
Topic: Omega dual-porosity model water content mass transfer
Replies: 3
Views: 151

Re: Omega dual-porosity model water content mass transfer

See also chapter 2.8. Water Mass Transfer in the manual. Yoy may perhaps get an approximate range if you use eq. 2.101 and replace conductivity with diffusivity. J.
by Jirka
Thu Aug 26, 2021 7:42 pm
Forum: Hydrus 1D
Topic: boundary condition of heat transport
Replies: 3
Views: 121

Re: boundary condition of heat transport

If you do not have measured temperatures at depth, then yes, I would use that. J.
by Jirka
Thu Aug 26, 2021 1:31 pm
Forum: Hydrus 1D
Topic: boundary condition of heat transport
Replies: 3
Views: 121

Re: boundary condition of heat transport

No, it does not. The zero gradient BC does not require any additional information. J.
by Jirka
Thu Aug 26, 2021 11:25 am
Forum: Hydrus 1D
Topic: Omega dual-porosity model water content mass transfer
Replies: 3
Views: 151

Re: Omega dual-porosity model water content mass transfer

a) Hydrus does not attempt to provide default values for any solute transport and reaction parameters (except for dispersivity and Freundlich exponent). b) Omega should be positive. The difference [Se_mo-Se_im] can be both positive or negative, resulting in mass transfer in one or the other directio...
by Jirka
Thu Aug 26, 2021 7:49 am
Forum: Hydrus 1D
Topic: model inverse - Evaporation experiment
Replies: 4
Views: 147

Re: model inverse - Evaporation experiment

See papers in:
Dane, J. H., and G. C. Topp (Eds.), Methods of Soil Analysis, Part 4, Physical Methods, Third edition, SSSA, Madison, WI, 139-157, 2002.

or any other Soil Physics textbook. J.
by Jirka
Wed Aug 25, 2021 10:22 am
Forum: HYDRUS (2D/3D)
Topic: Setting appropriate BCs
Replies: 5
Views: 168

Re: Setting appropriate BCs

You cannot apply boundary conditions properly without understanding their exact physical meaning. From that, it should be clear why “free drainage” can be used only at the bottom of the domain and not on its sides. If you understand that there is symmetry in the middle of the domain, which can corre...