# Mapping Pressure instead of Force **URL:** \ **Category:** Using preCICE\ **Tags:** fsi\ **Created:** [December 13, 2021, 7:11pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830 "2021-12-13T19:11:12Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![alicezanella](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/alicezanella/32/589_2.png) [@alicezanella](https://precice.discourse.group/u/alicezanella)\ **Post date:** [December 13, 2021, 7:11pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/1 "2021-12-13T19:11:12Z")
Hello preCICE users, I have a question about data mapping. First of all, do you think it is correct to transfer **pressure** instead of **forces**? If we do transfer pressure, aren’t we missing the viscous stresses? Since pressure is an intensive quantity (unlike force), do we need to use a consistent mapping? Regards, _Alice_ ---
**Author:** ![DavidSCN](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@DavidSCN](https://precice.discourse.group/u/DavidSCN)\ **Post date:** [December 13, 2021, 7:27pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/2 "2021-12-13T19:27:15Z")
> [@alicezanella](#): > > First of all, do you think it is correct to transfer **pressure** instead of **forces**? This depends on your coupling scenario. In standard FSI that’s true, you can not simply omit the viscous forces. In our OpenFOAM adapter, for example, we have an additional data set called _Stress_ including pressure and viscous contributions. The data is mapped consistently just like the pressure. ---
**Author:** ![alicezanella](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/alicezanella/32/589_2.png) [@alicezanella](https://precice.discourse.group/u/alicezanella)\ **Post date:** [December 13, 2021, 7:49pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/3 "2021-12-13T19:49:12Z")
Yes, my scenario is FSI and the adapter I’m working with is the openFOAM one. I’m already used to SU2, which I used with MBDyn, but I was curious about the type of quantities exchanged by OF. So _Stress_ is an intensive quantity, as it is pressure, right? That’s why the mapping is consistent. Is it possible to exchange forces instead of pressure, in OF? ---
**Author:** ![DavidSCN](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@DavidSCN](https://precice.discourse.group/u/DavidSCN)\ **Post date:** [December 16, 2021, 5:19pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/4 "2021-12-16T17:19:19Z")
> [@alicezanella](#): > > So _Stress_ is an intensive quantity, as it is pressure, right? That’s why the mapping is consistent. Is it possible to exchange forces instead of pressure, in OF? Intensive is (at least in my experience) a rather uncommon expression, but yes, _Stress_ ist intensive, just as _Pressure_. Yes, you can exchange _Forces_ instead of _Stress_. That’s also what most of our tutorial examples do in combination with OpenFOAM. IIRC, the FSI3 example is the only one which uses _Stress_ instead of _Force_. ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/precice/original/1X/67d2a5fa6f80e597e2267ff17fa8c1673cd11caa.svg) [@system](https://precice.discourse.group/u/system)\ **Post date:** [December 19, 2021, 5:19pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/5 "2021-12-19T17:19:54Z")
This topic was automatically closed 3 days after the last reply. New replies are no longer allowed. ---
**Author:** ![uekerman](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/uekerman/32/2199_2.png) [@uekerman](https://precice.discourse.group/u/uekerman)\ **Post date:** [December 20, 2021, 5:35pm UTC](https://precice.discourse.group/t/mapping-pressure-instead-of-force/830/6 "2021-12-20T17:35:14Z")
Overview of all data types supported by the OpenFOAM adapter: > **[The OpenFOAM adapter | preCICE - The Coupling Library](https://precice.org/adapter-openfoam-overview.html#what-can-it-do)** > > An OpenFOAM function object for CHT, FSI, and fluid-fluid coupled simulations using preCICE.