# Flow rate over time
**URL:** https://discourse.paraview.org/t/flow-rate-over-time/3115
**Category:** ParaView Support
**Created:** [December 4, 2019, 9:27am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115 "2019-12-04T09:27:13Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@vishruthdilip](https://discourse.paraview.org/u/vishruthdilip)
#### Post date: [December 4, 2019, 9:27am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/1 "2019-12-04T09:27:13Z")
Hello,
I use the MESHFREE solver. I wanted to know if there was a way to plot volume flow rate or mass flow rate across a surface over time.
I am relatively new to Paraview. Any help would be appreciated.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 4, 2019, 9:29am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/2 "2019-12-04T09:29:09Z")
What is the format of your data ?
Can you share a dataset ?
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### Author:  [@vishruthdilip](https://discourse.paraview.org/u/vishruthdilip)
#### Post date: [December 4, 2019, 9:39am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/3 "2019-12-04T09:39:41Z")
Its a case file. ENSIGHT binary format.
So there are two case files written, one for the boundaries (geometry) , and the other for the model (solution).
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 4, 2019, 9:53am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/4 "2019-12-04T09:53:01Z")
- Open your model
- Select the cells you want to inspect
- Filters -\> Extract Selection
- Filters -\> PlotDataOverTime
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### Author:  [@vishruthdilip](https://discourse.paraview.org/u/vishruthdilip)
#### Post date: [December 4, 2019, 10:08am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/5 "2019-12-04T10:08:08Z")
But I have not compute the mass flow.
Is it possible to compute the mass flow on Paraview and then plot it?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 4, 2019, 10:09am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/6 "2019-12-04T10:09:45Z")
You can implement any kind of computation using a Programmable Filter.
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### Author:  [@vishruthdilip](https://discourse.paraview.org/u/vishruthdilip)
#### Post date: [December 4, 2019, 10:19am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/7 "2019-12-04T10:19:58Z")
Isn’t there a filter already available to perform this computation?
- I could integrate the variables and use the Calculator filter. But the velocity is available only as vectors.
- Could you tell me how the surface flow filter works?
Even after computing the mass flow, can it be plotter over time?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 4, 2019, 10:25am UTC](https://discourse.paraview.org/t/flow-rate-over-time/3115/8 "2019-12-04T10:25:06Z")
> I could integrate the variables and use the Calculator filter. But the velocity is available only as vectors.
You can use the calculator with vectors.
> Could you tell me how the surface flow filter works?
The flow integration filter integrates the dot product of a point flow vector field and surface normal. It computes the net flow across the 2D surface. It operates on any type of dataset and produces an unstructured grid output of a single point containing the result.
> Even after computing the mass flow, can it be plotter over time?
Yes, use PlotDataOverTime