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FEMWATER problem

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Hi,

Has anyone else run into this problem, When I use the manual specifies the material elements, when i press “check simulation” the material show Warning: Kxx appears in the error values between elements 683 and 739 differ by more than 3 orders of magnitude. How can I solve this problem? thanks

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Hi,

Has anyone else run into this problem, When I use the manual specifies the material elements, when i press “check simulation” the material show Warning: Kxx appears in the error values between elements 683 and 739 differ by more than 3 orders of magnitude. How can I solve this problem? thanks

It's only a warning, the model should still run?

The Femwater manual recommends that the Ksat should not vary more than 3 orders of magnitude between adjacent elements (page 18). "If this rule is violated, the solutions will likely be inaccurate and probably slow to converge."

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It's only a warning, the model should still run?

The Femwater manual recommends that the Ksat should not vary more than 3 orders of magnitude between adjacent elements (page 18). "If this rule is violated, the solutions will likely be inaccurate and probably slow to converge."

Yes, the model still run, thanks.

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I have a new question, I run model display the error: total nodes and elements did not match 2887 4737. How do I solve this problem?

It's something wrong with the way you have constructed the 3D mesh. How did you do it?

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It's something wrong with the way you have constructed the 3D mesh. How did you do it?

I'm use Boreholes, Horizon to 3d mesh, in meshing options:

minimum element thickness, i choose 1m.

refind elements, i choose refind layers with pyramid elements.

subdivide material layers, i choose target layer thickness.

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I'm use Boreholes, Horizon to 3d mesh, in meshing options:

minimum element thickness, i choose 1m.

refind elements, i choose refind layers with pyramid elements.

subdivide material layers, i choose target layer thickness.

Try using wedge/pentahedral elements.

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Sorry, How do I use the wedge / pentahedral to 3d mesh?

So I haven't used boreholes, horizon to 3D mesh.

But when you do this, what kind of elements does it give you?

Femwater has 3 kinds

- hexahedral (8 nodes, 6 faces)

- pentahedral (6 nodes, 5 faces) * this is the best one to use *

- tetrahedral (4 nodes, 4 faces)

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So I haven't used boreholes, horizon to 3D mesh.

But when you do this, what kind of elements does it give you?

Femwater has 3 kinds

- hexahedral (8 nodes, 6 faces)

- pentahedral (6 nodes, 5 faces) * this is the best one to use *

- tetrahedral (4 nodes, 4 faces)

If the meshing options i did not choice refind elements,most of the grid is pentahedral, but some are tetrahedral, and i press the check simulation option displays Error: Element 1 is a five nodes element etc.

If i use horizon to 3D mesh and run model, that will be displays error:total nodes and elements did not match 7206 36336. and how to do solve this problem?

Edited by 9919704

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If the meshing options i did not choice refind elements,most of the grid is pentahedral, but some are tetrahedral, and i press the check simulation option displays Error: Element 1 is a five nodes element etc.

If i use horizon to 3D mesh and run model, that will be displays error:total nodes and elements did not match 7206 36336. and how to do solve this problem?

Femwater can't do 5 nodes element (even though GMS supports them) and doesn't work very well for 4 node and 8 node elements, in my experience.

One thing you can do is to renumber the element, that might help; in 3D Mesh mode, select a boundary face, then choose renumber in the Mesh menu. Then try running the model again.

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Femwater can't do 5 nodes element (even though GMS supports them) and doesn't work very well for 4 node and 8 node elements, in my experience.

One thing you can do is to renumber the element, that might help; in 3D Mesh mode, select a boundary face, then choose renumber in the Mesh menu. Then try running the model again.

I had solved this problem, thank you, and i have other problem need help,

1.Now my computer display legend is random code, and my computer system is win 7, that is good before.

2.In initial conditions, I use hot start and save, that display "your output pressure head filename is the same as your initial condition pressure head file name. The initial condition file will be overwritten. select OK to continue or cancel stop." that is OK?

Edited by 9919704

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I had solved this problem, thank you, and i have other problem need help,

1.Now my computer display legend is random code, and my computer system is win 7, that is good before.

2.In initial conditions, I use hot start and save, that display "your output pressure head filename is the same as your initial condition pressure head file name. The initial condition file will be overwritten. select OK to continue or cancel stop." that is OK?

It's better to put your initial conditions in a separate file. I usually copy the phd solution file and rename to add an "i", like projectnamei.phd

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It's better to put your initial conditions in a separate file. I usually copy the phd solution file and rename to add an "i", like projectnamei.phd

Thank you for your answer,and I have some questions:

1.material input the compressibility is the Modified compressibilty?

2.In van Genuchten Curve Generator, What does that mean of Max. height above water table?

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Thank you for your answer,and I have some questions:

1.material input the compressibility is the Modified compressibilty?

2.In van Genuchten Curve Generator, What does that mean of Max. height above water table?

1. No, it's not the modified compressibility. Femwater calculates the modified compressibility.

2. Max height above the water table is the minimum tension that the curve generator calculates. So if you put 10 (metres say), the van Genuchten curve generator will calculate curves from 0 to -10 m tension. (If the model has tensions lower than -10, the -10 value will be used.)

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1. No, it's not the modified compressibility. Femwater calculates the modified compressibility.

2. Max height above the water table is the minimum tension that the curve generator calculates. So if you put 10 (metres say), the van Genuchten curve generator will calculate curves from 0 to -10 m tension. (If the model has tensions lower than -10, the -10 value will be used.)

So, if my length unit is metres, then Max height above the water table is metres too?

i have problem,i use flow bc and flow value is transient, then put in

time(h) flow trans.(m/h)

1 0.005

24 0.01

48 0.05

72 0.01

why i run model show xy1 card:the XY series card =13059 > MXXYS=250 stop?

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It's saying you have more than 250 XY series in your model data, which is the maximum allowed.

Do you have a large number of boundary conditions? If so, you will need to recompile FEMWATER with a larger value of MXXYS in the gwpara.inc file.

If not, if you have made many modifications to your model, it could be a bug in GMS that is causing the error by not deleting old XY series in the 3bc file. Can you recreate your model from scratch? Or manually delete obsolete XY1 series in the 3bc file.

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It's saying you have more than 250 XY series in your model data, which is the maximum allowed.

Do you have a large number of boundary conditions? If so, you will need to recompile FEMWATER with a larger value of MXXYS in the gwpara.inc file.

If not, if you have made many modifications to your model, it could be a bug in GMS that is causing the error by not deleting old XY series in the 3bc file. Can you recreate your model from scratch? Or manually delete obsolete XY1 series in the 3bc file.

Thank you, i has solve this problem. i manually delete obsolete XY1 series in the 3bc file.

If I have a model, there are three tiers from top to bottom (A、B and C);(A and B ) is the permeable layer, C layer is impermeable layer; If I want to only allow groundwater exists in the c layer above, C under no groundwater, and A layer exists above the rain. If I adding flow on back boundary. The front boundaries use constant head. If I use steady, the groundwater to fill my study area. If use transient, then Simulation time more than 600HR…how can I to solve this problem?

Edited by 9919704

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Thank you, i has solve this problem. i manually delete obsolete XY1 series in the 3bc file.

If I have a model, there are three tiers from top to bottom (A、B and C);(A and B ) is the permeable layer, C layer is impermeable layer; If I want to only allow groundwater exists in the c layer above, C under no groundwater, and A layer exists above the rain. If I adding flow on back boundary. The front boundaries use constant head. If I use steady, the groundwater to fill my study area. If use transient, then Simulation time more than 600HR…how can I to solve this problem?

Steady state should work. Sounds like your boundary conditions might be wrong. Or your hydraulic conductivity. Have you checked the units of all the boundary conditions? They must be consistent.

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Steady state should work. Sounds like your boundary conditions might be wrong. Or your hydraulic conductivity. Have you checked the units of all the boundary conditions? They must be consistent.

thank's for your answer. I has check units of all the boundary conditions, In my B layer the hydraulic conductivity is 0.4(m/h),and C layer the hydraulic conductivity is 3.6*10^-6(m/h).

The front boundary only to B layer is constant head is 10.336m(for one Atmospheric pressure), and back boundary only to B layer has one row flow(0.1 m/h).and i don't know my Practice is ok? or has better solve methods?

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thank's for your answer. I has check units of all the boundary conditions, In my B layer the hydraulic conductivity is 0.4(m/h),and C layer the hydraulic conductivity is 3.6*10^-6(m/h).

The front boundary only to B layer is constant head is 10.336m(for one Atmospheric pressure), and back boundary only to B layer has one row flow(0.1 m/h).and i don't know my Practice is ok? or has better solve methods?

What is the elevation of your 3 layers? Is there any recharge?

feel free to mail me directly...

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What is the elevation of your 3 layers? Is there any recharge?

feel free to mail me directly...

What is your e-mail?

My model bottom elevation is 280m, top elevation is 320m. In 280m-305m is C layer, in 305m-315m is B layer, 315m-320m is A layer.

In back boundary of B layer has one row flow, and in top boundary has rain, and in front boundary of B layer has constant head 10.336m.

Initial conditions i choose "compute from constant total head" total head 280m.

Edited by 9919704

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What is your e-mail?

My model bottom elevation is 280m, top elevation is 320m. In 280m-305m is C layer, in 305m-315m is B layer, 315m-320m is A layer.

In back boundary of B layer has one row flow, and in top boundary has rain, and in front boundary of B layer has constant head 10.336m.

Initial conditions i choose "compute from constant total head" total head 280m.

Heads supplied to Femwater are total head not pressure head. So you need to add 280 to your front boundary condition.

Your initial head should be in the range 280-320, but I think it should be >280.

My email is simon dot woodward at lvl dot co dot nz

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Heads supplied to Femwater are total head not pressure head. So you need to add 280 to your front boundary condition.

Your initial head should be in the range 280-320, but I think it should be >280.

My email is simon dot woodward at lvl dot co dot nz

thanks, simon.

i has email to your email.

if you get it, please tell me.

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thanks, simon.

i has email to your email.

if you get it, please tell me.

Yes, I got it, and I already replied.

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