# preCICE adapter for MBDyn solver for beam elements **URL:** \ **Category:** Official adapters and tutorials\ **Tags:** openfoam, adapters, mbdyn, fsi, inactive\ **Created:** [May 5, 2020, 12:29pm UTC](https://precice.discourse.group/t/precice-adapter-for-mbdyn-solver-for-beam-elements/239 "2020-05-05T12:29:03Z")\ **Posts on this page:** 1\ **Showing post:** 6
**Author:** ![Claudio](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@Claudio](https://precice.discourse.group/u/Claudio)\ **Post date:** [July 2, 2020, 3:29pm UTC](https://precice.discourse.group/t/precice-adapter-for-mbdyn-solver-for-beam-elements/239/6 "2020-07-02T15:29:03Z")
Hi @Makis , of course I will. I have just concluded some simulations and I’d like to share some of the results. As I first wanted to validate the adapter, I focused on the Turek-Hron benchmark which is one of the tutorials (this is named FSI3 in the paper). At the moment I am still not able to overcome instability due to mass ratio (solid/fluid) close to 1. So I decided to consider the other benchmark (named FSI2) which has a mass ratio of 10. My results, considering the tip movement, are the following: ![FSI2_displacements](https://global.discourse-cdn.com/free1/uploads/precice/original/1X/8ee1630e284841267dad85f839bf030bffdf6526.png) The y displacement has a mean value of 3.35mm with an amplitude 83.9mm and a period of 586ms. The reference has a mean of 1.23mm with an amplitude of 80.6mm. The x displacement has a mean value of -14.54mm and an amplitude of 11.65mm and a period of 293ms. The reference has a mean -14.56mm and an amplitude of 12.44mm. I’ve got also other data but I’d like to keep the focus of the post on the configuration aspects and open points: - I need to use a progression of forces: the MBDyn mesh is the same as the PreCICE Solid mesh. The forces on the PreCICE nodes coming form the coupling are passed to MBDyn multiplied by a coefficient: ![scale_FSI2](https://global.discourse-cdn.com/free1/uploads/precice/original/1X/087a1f527ecd514926fb2c10a942e8c8c1d42697.png) the first 500ms are used to let the fluid settle, and then for the next 500ms the forces are increased. The slope of the coefficient is really critical for convergence. A steeper slope makes the computation unstable. But this way the simulation requires more time. - I have been using the following coupling parameters: 1. The convergence measures require quite a lot of iterations to converge: 2. I can only use _Fluid_ as second participant beacuse otherwise I have issues. But I would be interested in trying other configurations. I would be interested in discussing some ways to speed-up the convergence and finding a way to overcome the issues regarding the mass ratio. I am going to update this post when I have new findings best regards Claudio --- _[View the full topic](https://precice.discourse.group/t/precice-adapter-for-mbdyn-solver-for-beam-elements/239)._