Modelling FSI problems in ANSYS Fluent via UDF

Fluid-Structure Interaction (FSI) A Fluid-Structure Interaction model is needed when: there are heavy fluid actions on deforming boundaries it is not possible to neglect deformations phenomena are coupled and it is not possible to study the problem separating the structural and fluid effects e.g. Hemodynamics FSI problem

Benefits of FSI Simulation Investigate if problems are coupled Determine global performance difference comparing with the rigid case Analyze local flow field changes Analyze structural dynamic behaviour Structural verification Investigate if problems are physically stable/unstable and determine transition conditions

The Proposed Product The Product aim is to allow FSI problems simulation entirely within ANSYS Fluent A dedicated FEM solver has been developed by means of UDF coding as plug in for ANSYS Fluent Dedicated Graphical User Interface (GUI) and Text User Interface have been developed The Product has been tested, validated and used to simulate practical and industrial cases

Our Strategy New: The product allows to set structure material More Time Steps ? NO POST - PROCESSING CFD Mesh CFD Materials CFD Iterations CFD BCs FEM Materials FEM BCs Next Timestep New: The product allows to set structure material properties and constraints in the ANSYS FLUENT code. Convergence ? NO INITIALIZATION Remeshing / Smoothing Pressures, shear stresses and contact forces Displacements FEM Mesh is built FEM Iteration New geometry from CFD one

Product Features General robust FEM solver implemented Structural simulations in the range of small and large displacements, including non linear and contact problems 2D model for beams with implicit and explicit FEM approach 3D model for shells structure with implicit and explicit FEM approach Parallel implementation Static and dynamic transient analysis Multiphase and turbulence ANSYS Fluent model Post-processing with ANSYS Fluent

Product strengths High efficiency Very light General purpose The result is a very light code that leaves almost unaffected the global CPU time High efficiency Very light General purpose ANSYS Fluent users oriented There are no interpolation errors No other software knowledge is required Highly customizable for client-oriented solutions, services and consultancy.

Graphical User Interface Dedicated GUI in ANSYS Fluent

The CFD point of view Very often FSI problems are analysed by a structural point of view simulating the fluid with too simplified models The present approach uses the CFD point of view (ANSYS Fluent users point of view), focusing on how the interaction with the structure influences the fluid behaviour The CFD user is now allowed to set structure material properties and constraints in order to easily simulate its presence in a very family way The knowledges of other software packages are not required

Example of 3D model for shells structure (1) FSI Interaction between a rectangular curtain and an air flow in a room. This is an example in which because there are heavy fluid actions on the curtain surface and so it is necessary to consider its deformations it is not possible to study the problem separating structural and fluid effects WINDOW DOOR CURTAIN

Example of 3D model for shells structure (2) HW & SW configuration Hardware: 2 AMD Opteron 2,2GHz Processor 16Gb RAM Software: OS Linux Fedora 6 ANSYS Fluent Version 6.3.23 Version: 3ddp Structural analysis solver used: Explicit

Example of 3D model for shells structure (3) Case 1: The curtain has the top edge constrained. It’s moved by the air flow entering from the window and subjected to its dead load.

Example of 3D model for shells structure (4) Case 2: In this case the event of failure of curtain support is investigated. The curtain is pushed by the air flow entering from the window and it’s free to fall because the top edge constraint is missing.

Example of related areas Hemodynamics and FSI Fluid-Structure Interaction In this branch of medicine is necessary to consider the interaction between the flowing blood and the vessels walls in order to investigate and study many hemodynamics problems. HW & SW configuration Hardware: 2 AMD Opteron 2,2GHz Processor 16Gb RAM Software: OS Linux Fedora 6 ANSYS Fluent Version 6.3.23 Version: 3ddp Structural analysis solver used: Implicit solver working with MSC.NASTRAN solver

Example of hemodynamics problem (1) The following picture represents the model of a Systemic-to-pulmonary shunt that is a surgical procedure to treat complex congenital heart defects. It consists of an interposing tube between the sub-clavian artery and the right pulmonary artery. In this case it’s important to analyze the pressure drop across the shunt which is affected by the blood pressure combined with the distensibility of the shunt.

Example of hemodynamics problem (2) SHUNT

University of Rome Tor Vergata Contact University of Rome Tor Vergata Dept. Mechanical Engineering Via del Politecnico,1 – Rome, ITALY e-mail: fsi-project@torvergata-karting.it Tel: +39 06 7259 7124 - Dr. Marco E. Biancolini