# About "compute mapping" function in precice **URL:** https://precice.discourse.group/t/about-compute-mapping-function-in-precice/1937 **Category:** Using preCICE **Tags:** fsi **Created:** [May 25, 2024, 4:49am UTC](https://precice.discourse.group/t/about-compute-mapping-function-in-precice/1937 "2024-05-25T04:49:57Z") **Posts on this page:** 2 **Page:** 1
### Author: ![ilovenili](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/ilovenili/32/1663_2.png) [@ilovenili](https://precice.discourse.group/u/ilovenili) #### Post date: [May 25, 2024, 4:49am UTC](https://precice.discourse.group/t/about-compute-mapping-function-in-precice/1937/1 "2024-05-25T04:49:57Z")
hi,precice: ![image](https://global.discourse-cdn.com/free1/uploads/precice/original/2X/c/ce04d9a68b5223d2e15f66ab8319a1971210ae5a.png) I’m currently using the ALE method to implement a moving mesh that implements fluent, and I see that the official website says that precice’s mesh mapping is based on a reference domain, so I have two questions: 1 Fluent’s reference domain changes every time step when using dynamic mesh, which means it needs to do mesh mapping every time step to be reasonable, but precice only calls “compute mapping” once, how to explain this? 2 For perpendicular flap case, is it necessary to calculate the mesh mapping matrix at every time step, Similar to calls “compute mapping” every time step, and why? ---
### Author: ![fsimonis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/fsimonis/32/6_2.png) [@fsimonis](https://precice.discourse.group/u/fsimonis) #### Post date: [June 24, 2024, 8:58am UTC](https://precice.discourse.group/t/about-compute-mapping-function-in-precice/1937/2 "2024-06-24T08:58:40Z")
Hi, > [@ilovenili](#): > > Fluent’s reference domain changes every time step when using dynamic mesh Meaning that you aren’t using a static reference domain. This isn’t ALE. > [@ilovenili](#): > > For perpendicular flap case, is it necessary to calculate the mesh mapping matrix at every time step, Similar to calls “compute mapping” every time step, and why? RBF mappings require solving a system when mapping data. The mapping section of our latest reference paper explains this in detail.