Learning Forum

[Atif Ismail]

Hello everyone, 
I am working on hydrualic fracturing simulation using fluid solid coupling (mechanical and fluent). 
The objective of my study is to assess the fracture attributes after specific injection of fluid in the rock. I have few questions, kindly if anyone may assist. 

1) How to find the fracture width and length at the end of simulation in fluid solid coupled system? 

2) Is there any way to select the pre-existing semi elliptical fracture face front as a solid fluid coupling region; I want to apply the pressure from fluent to face of the fracture. 

3) Can we apply the smart fracture growth module in the fluid solid coupled simulation? 

Regards, 

[Rahul]

You can post-process the results of coupling analysis by opening results in participant solver or ensight to determine the fracture dimensions. Postprocessing System Coupling's Co-Simulation Results (ansys.com)

The System Coupling option must be selected on the desired moving and deforming wall boundaries in order to obtain displacements from other co-simulation participants taking part in the coupled analysis. 42.5. System Coupling Related Settings in Fluent (ansys.com)

I recommend going over this tutorial in the Ansys documentation that shows a 2-way FSI simulation with Fluent and Mechanical. Reed Valve FSI Co-Simulation with Partial Setup Export from Workbench (Fluent-Mechanical) (ansys.com) 

You can also look at the following for a similar tutorial but run with the System Coupling GUI outside of Workbench. The new System Coupling GUI (run outside of Workbench) is available by searching for System Coupling 2019R3 (or newer) in the Windows Start menu.

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_tut/sysc_tut_reedvalve_fluent.html

FSI simulations with very soft materials or membranes are prone to numerical instabilities. In 2020R1 we have introduced a stabilization method in System Coupling called the Quasi-Newton Stabilization Algorithm. Note that this has to be used with the new System Coupling GUI or Command Line Interface that is run outside of Workbench. More information here:https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_ug/sysc_gen_scservice_dt_supplemental_iqnils.html

It is very important to build up the FSI simulation in stages as opposed to setting up the 2-way FSI right at the start. This document Best Practices for Coupled Fluid-Structure Interaction (FSI) describes this process and is available here:Best Practices for System Coupling (ansys.com)

 

[Atif Ismail]

Thanks a lot for your valuable information. I am in communication with IT department of my University to access the shared resources by you for the clarification of my questions.

I am trying to run a hydromechanical simulation by 2way coupling of fluent and structural. The material tight sandstone from geomechanical materis. I tried to add SMART crack growth but it was giving me "?" in coupling region. Can we add any fracture propagation mechanism in 2way coupling for hydraulic fracturing mechanism in the rock? 
Regards,

[Erik Kostson]

 

 

Hi

I doubt very much that this is possible to do (2 way FSI with crack growth).

Also Sandstone uses or should use some form of Drucker or Mohr Nonlinear material model, which are not applicable with Smart Crack Growth which only supports Material behavior that is linear elastic isotropic.

Think this type of analysis is very complex and needs a tailored 'inhouse' solution as perhaps this one:

https://scholar.google.com/scholar?q=Coupled+hydromechanical-fracture+simulations+and+three-dimensional+hydraulic+fracture+propagation&hl=en&as_sdt=0&as_vis=1&oi=scholart

 

 

All the best

Erik