# Calculate seepage force
**URL:** https://forum.itascainternational.com/t/calculate-seepage-force/761
**Category:** FLAC3D
**Created:** [September 27, 2022, 6:51pm UTC](https://forum.itascainternational.com/t/calculate-seepage-force/761 "2022-09-27T18:51:48Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Gian](https://forum.itascainternational.com/u/Gian)
#### Post date: [September 27, 2022, 6:51pm UTC](https://forum.itascainternational.com/t/calculate-seepage-force/761/1 "2022-09-27T18:51:48Z")
Hello guys,
quick question, would you suggest me a method to calculate the seepage force **vector** at gridpoint level? The model is one-way coupled fluid-\>mech.
I only managed to estimate seepage force module at gridpoints (using gp.flow, as float) and force vector at zones (zone.flow, as vector).
Thanks,
Gian
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### Author:  [@Rabanser](https://forum.itascainternational.com/u/Rabanser)
#### Post date: [August 6, 2024, 3:17pm UTC](https://forum.itascainternational.com/t/calculate-seepage-force/761/2 "2024-08-06T15:17:03Z")
Is there already a solution for this query? I’m trying to solve the same “problem”
Thanks!
Josef
---
### Author:  [@cheng](https://forum.itascainternational.com/u/cheng)
#### Post date: [August 8, 2024, 4:42pm UTC](https://forum.itascainternational.com/t/calculate-seepage-force/761/3 "2024-08-08T16:42:55Z")
Currently it cannot be directly output. But again, we can use a small simple FISH function to do the job (Thanks, FISH!). We can loop all gridpoints, calculable the gridpoint flow by averaging flows of its neighboring zones with weights of zone volumes. We can then use the **user defined vectors** to visualize the gridpoint flow. Below is an example
```auto
model restore "ch2a.sav"
fish define calc_gp_flow
loop foreach local g gp.list
local gp_flow = vector(0,0,0)
local z_vol = 0.0
loop foreach local z gp.zone(g)
zvol = zone.vol(z)
gp_flow = gp_flow + zone.flow(z)* zvol
z_vol = z_vol + zvol
endloop
gp_flow = gp_flow/z_vol
zp = data.vector.create(gp.pos(g))
data.vector.value(zp) = gp_flow
endloop
end
[calc_gp_flow]
```
Then plot the **user defined data** → **vector** :
