NUMERICAL MODELLING OF MECHANICAL COUPLING IN FLUIDS & STRUCTURES SOFTWARE fluidyn - MP

PRESENTATION OF fluidyn - MP

General : role & utility of Computational Fluid Dynamics A reliable numerical representation of a real processus with the help of well adapted physical models Easy to use & adapted to optimisation studies in industrial processes Economic with a security advantage Ideal complementary tool for experimental measurements Access to physical variables (velocities, pressure, temperature, etc.) at each point in the domain

Software fluidyn - MP, FSI model Strong coupling & conjugate heat transfer between fluid & structures integrated in a single software platform Robust physical models & various well adapted solvers Finite Volume Method for fluids and Finte elements method for structures Automatic exchange of boundary conditionsbetween fluids & structures - Adaptative Fluid Mesh Automatic exchange of boundary conditions between fluids & structures - Adaptative Fluid Mesh Local time step usedto reduce CPU time Local time step used to reduce CPU time

3-Dimensions Compressible / incompressible Mechanical / thermal shocks Viscous / non-viscous Laminar / turbulent Multi-species Multi-phase Solution of Navier-Stokes Equations Fluid Solver

Non-Newtonian Flows : Bingham law Power law Chemical – combustion reactions Arrhenius model Eddy-break-up model Eddy dissipation model Deflagration & fire BLEVE Pool fire Detonation JWL model Two phase flows droplets, bubbles, particles Euler-Lagrange Monte-Carlo, Free surface flow ( VOF method + CSF method) Fluid Solver

Free surface two phase flows VOF method (Volume of Fluid) Finite volumes solution Adapted to gravity controlled flows whose interfaces undergo large deformations 3 high order convective schemes (Inter-Gamma Differencing, HRIC & CICSAM) CSF method (Continuum Surface Force) for modelling surface tension

Fluid Solver Free surface two phase flows ALE method (Arbitrary Lagrangian Eulerian) Finite volumes solution adapted to problems needing a fine modelling & whose interface undergoes small deformations 2 solution algorithms : Donor Cell (1 st order) & Van Leer (2 nd order) easy calculation of surface tension

Fluid Solver Two phase Euler / Lagrange flows Euler / Lagrange method adapted to flows with the presence of a dispersed phase diluted or dense flows monitoring each particle trajectory jet, fluid bed flows modelling, etc.

Fluid Solver Two phase Euler / Lagrange flows Particle size distribution various distribution methods : uniform, gaussian, Rosin- Rammler type, Nukiyama-Tanasawa type, user routine non uniform distribution : statistic method of Monte-Carlo wall interaction accounted for via a restitution coefficient modelling inter-particle collisions, coalescence phenomena, rupture & agglomeration

Algebraic Models  Baldwin- Lomax Mixing Length :  Van Driest damping  Abbott & Bushnell  Cebeci- Smith Sub grid scale model SGS Two equations transport (k -  ) & RNG Reynolds stress model (anisotropic turbulence) Turbulence Fluid Solver

Perfect gas Ideal gas JWL (Jones - Wilkins - Lee) for explosions Linear - polynomial User defined Equations of State Temperature functions User defined Viscosity & Prandtl number Fluid Solver

Spatial discretization schemes Explicit : Van Leer Flux Vector Splitting Roe Flux Difference Splitting 3 rd order Advection Upwind Splitting, HLLC Semi- implicit : Weighted Upwind Scheme QSOU 2 rd order Implicit : Central Difference Scheme 3 rd order Flux Limiter Scheme (Van Leer, SMART, etc.) Fluid Solver

Explicit : Time step  global minimum for transient simulations  local for steady state simulations convergence acceleration Temporal Integration  6 step 2 nd order Runge Kutta. Implicit: Gauss-Seidel or Jacobi iterative methods steady state calculation & low velocities. Temporal discretization scheme Fluid Solver

FINITE ELEMENTS 3D beam elements 3 node shell elements 4 node tetrahedral elements Material characteristics Linear elasto-plastic, orthotropic Piecewise linear Non linear plastic Structured solver

Structured Solver Small deformations & large displacements Finite Elements method Large deformations Finite Elements method Finite Elements solvers Explicit / implicit Rayleigh damping

Boundary Conditions Transient or constant Outside : at nodes : temperature, forces, displacements at faces: pressure, volume forces Imposed automatically in fluids & structures Modelling displacement of fluid mesh with Updated Lagrangian method Structured solver

Automatic simulation of convective & radiative heat transfer Radiation models Transparent media  Automatic calculation of 3D view factors  Shadow effect of intermediate obstacles Opaque Media  Six-Flux model  Discrete ordinate model Thermal analysis  Material properties w.r.t temperature  Conduction with Finite Elements method. Heat transfer modelling

Computation Procedure - 4 steps FLUID-STRUCTURE REMESHING Iterations until convergence Fluid solver Fluid temperature Heat transfer coefficient Distribution of boundary pressures Thermal solver Transient heat transfer Solid temperature Structured solver Thermal load Mechanical load (pressure) stress & deformations

Multi-block structured Un-structured  Delaunay method  2D & 3D meshes  Hybrid, tetrahedral or hexahedral mesh Adaptative mesh  Shocks, turbulent boundary layers,..  Refined mesh & automatic interpolation of the solution. Interactive, simple & automatic Complex geometries Mesh Pre - processor

Geometry & computation parameters visualisation during simulation. 3D colour visualisation. Multi-viewport facility : upto 30 viewports Comparison of results obtained from different computations Vectors, iso-contours, iso-surfaces & 3D current lines Translations, rotations, multi projections XY plots: residual & other parameters Animations Post - processor

Fluidyn - MP : STUDY CASES FLUID – STRUCTURE MECHANICAL INTERACTIONS DOOR OPENING UNDER FLUID PRESSURE DOOR OPENING UNDER FLUID PRESSURE FLAPGATE OPENING UNDER FLUID PRESSURE FLAPGATE OPENING UNDER FLUID PRESSURE AEROSPACE TOBOGGAN TNT EXPLOSION TNT EXPLOSION TUNNEL (BOURGES) TUNNEL (BOURGES)

fluidyn-FSI FLUID – STRUCTURE INTERACTION Simulation of large displacements & large structural deformations due to fluid movements STRONG COUPLING by 2 METHODS Finite Volumes (FV) for fluids Finite Elements (FE) for solids

Calculation Procedure - 4 steps FLUID-STRUCTURE REMESHING Iterations until convergence Fluid Solver Fluid Temperature Coefficient of heat transfer Pressure distribution at the boundaries Heat Solver Transfer of transient heat Temperature in solids Structured solver Heat load Mechanical loads (pressures) stress & deformations fluidyn - FSI

STUDY 1 : OPENING OF A DOOR UNDER FLUID PRESSURE

TARED DOOR DESCRIPTION - Opening of a door under fluid pressure effect. - Modelling with the help of the software Fluidyn - FSI DESCRIPTION - Opening of a door under fluid pressure effect. - Modelling with the help of the software Fluidyn - FSI Porte -----> Chambre à 30 bar fluidyn - FSI

RESULTANT OF DISPLACEMENT IN THE DOOR fluidyn - FSI

DOOR DEFORMATION fluidyn - FSI

PRESSURE CONTOUR fluidyn - FSI

PRESSURE CONTOUR fluidyn - FSI

PRESSURE CONTOUR fluidyn - FSI

PRESSURE CONTOUR fluidyn - FSI

STUDY 2 : OPENING OF A FLAPGATE UNDER THE EFFECT OF FLUID PRESSURE

fluidyn - FSI - A flapgate situated at the end of a pipe opens under the action of fluid flow - Modelling with the help of Fluidyn - MP - fluid = water, inlet velocity = 1.07 m/s - flapgate = steel slab - 3D flow, strong coupling between fluid & structure PROBLEM

GEOMETRY OF THE PROCESS fluidyn - FSI

DOMAIN MESH Fluid = Finite Volumes Structure = Finite Elements fluidyn - FSI

FLOW IN THE MEDIAN PLANE fluidyn - FSI

FLUID PRESSURE ON THE STRUCTURE fluidyn - FSI

FINAL STATE fluidyn - FSI

STUDY 3 : WIND RESISTANCE OF AN ESCAPE CHUTE

DESCRIPTION Wind resistance of an escape chute submitted to a lateral wind of 25 nodes Simplified Case : isolation des arcs & the runways for the simulations Structural Modelling with the help of finite elements of beam type Fluid Modelling (air) with the help of finite volumes Results searched for : deformations & maximum stress DESCRIPTION Wind resistance of an escape chute submitted to a lateral wind of 25 nodes Simplified Case : isolation des arcs & the runways for the simulations Structural Modelling with the help of finite elements of beam type Fluid Modelling (air) with the help of finite volumes Results searched for : deformations & maximum stress PRESENTATION

CHARACTERISTICS

FLUID MESH

STRUCTURAL MESH

BOUNDARY CONDITIONS

RESULTS : DEFORMATIONS

RESULTS : RESULTANT OF DISPLACEMENT

RESULTS : AERAULICS AROUND THE CHUTE

STUDY 4 : TNT EXPLOSION IN A TUNNEL STUDY OF ASSOCIATED DEFORMATIONS

DESCRIPTION TNT Explosion in a cylindrical section of a T tunnel dimensions : diameter = 168 mm, lengths = 1.28 m & 1.50 m Tunnel walls in steel, thickness = 2 mm TNT Load of 18.5 g placed at the tunnel head Results searched for : propagation of detonation wave, final structural deformation DESCRIPTION TNT Explosion in a cylindrical section of a T tunnel dimensions : diameter = 168 mm, lengths = 1.28 m & 1.50 m Tunnel walls in steel, thickness = 2 mm TNT Load of 18.5 g placed at the tunnel head Results searched for : propagation of detonation wave, final structural deformation PRESENTATION

GEOMETRY

MATHEMATICAL MODEL JWL equation for TNT Ideal gas for air

JWL EQUATION COEFFICIENTS  0 = 1630 kg/ m 3 A= E 0 = 7 GJ/m 3 B= P cj = 0.21 MbarR 1 = 4.15 D cj = cm/  sR 2 = 0.9  cj = 0.3  cj = 2.727

STEEL PROPERTIES Elasticity Module = 210 GPa Poisson Coefficient= 0.3 Density= 7850 kg/m 3

BOUNDARY CONDITIONS : FLUID

BOUNDARY CONDITIONS : STRUCTURE

FLUID MESH

STRUCTURAL MESH

3D SIMULATION Symmetry (in the Y direction perpendicular to the tunnel plane) : mesh reduced to half of the domain 3D domain extended beyond the tunnel head in order to place the TNT charge 3D Mesh –48972 cells for the fluid –9128 elements for the structure

RESULTS : PICS OF THE PRESSURE AT MONITOR POINTS

RESULTS : COMPARISON WITH EXPERIMENTAL RESULTS P (bar) ExperimentalComputed Trace Point P (bar) G G G G1 Time (ms) Time (ms)

RESULTS : PRESSURE WAVE PROPAGATION

RESULTS : DISPLACEMENT STRESS IN THE STRUCTURE

RESULTS : DEFORMED FINAL STATE OF THE STRUCTURE

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