Vista: A Multi-field Object Oriented CFD-package T. Kvamsdal 1, R. Holdahl 1 and P. Böhm 2 1 SINTEF ICT, Applied Mathematics, Norway 2 inutech GmbH, Germany
Outline inutech & SINTEF VISTA a CFD Solver VISTA a CFD Toolbox Extrusion example: Extrud3D
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VISTA A CFD-Solver
VISTA: A Multi-field Object Oriented CFD-package + Heat-Problem + ALE Vista Extrud + Free-surface flow + Turbulence Vista Marine Incompressible Navier-Stokes equation: + Fluid-structure Interaction Bloodflow-Problem 1 (based on VISTA) 1 phd-thesis Runar Holdahl
VISTA Marine Viscous 3D flow around a cylinder, Re=265, velocity isosurface Large-eddy simulation of flow around two cylinders in a tandem arrangement, Re=22000, velocity isosurface and pressure distribution
Computational Facts Block structured, 8 node hexahedral FE-elements LES-turbulence model (Smagorinsky, Van Driest) Number of time steps: 5000 Number of grid points: 770 982 Total no. of degrees of freedom: 3 083 928 Number of processors: 96 Parallel computers necessary for addressing this case!
Feature List Incompressible flow Stokes/Navier-Stokes 2D/3D stationary and time dependent variable density Turbulence modeling LES (Smagorinsky with van Driest damping) RANS (k-e: High Reynolds model) Reference system and boundary conditions ALE formulation Moving object (FSI) Free surface Periodic boundary conditions General boundary conditions (Dirichlet/Neumann) Numerical approximation (Mixed) finite elements (Taylor-Hood, equal order) Continuous projection method (including incremental pressure formulation) Semi-implicit BDF time discretisation Parallel Krylov solver reconditioned with two-level domain decomposition Software issues Usage Object-oriented (c++) code based on Diffpack Platform independent (running on Unix/Linux) Parallelised with MPI Preprocessor: GRIDDLER Postprocessor: GLview, VTK, Matlab (2D) NTNU/SINTEF: Free usage for education and research
VISTA A CFD-Toolbox
The VISTA Vision Navier-Stokes related problem VISTA Plug and Play related problem + = (+ (+ Diffpack) own coupled CFD solver Heat-Problem Turbulence Free-Surface Fluid-Surface- Interaction
The Diffpack Vision s = F t ( v, s, t ) arbitrary PDE, ODE, or or other numerical problem [ κ u] f in = Ω u = g on Ω Diffpack Kernel + = own Diffpack Toolboxes (further extensions) own solver
Philosophy: Plug and play Divide et Impera! Problem1 Problem2 SimCase Data transfer by: get -functions attach -functions CoupledSolver Solver1 Solver2 Solver3
Example 1: Free-surface flow InterfaceProblem ALEproblem FluidProblem FreeSurfaceSolver SimCase InterfaceSolver FluidSolver MeshMover
Vista Software - Current and Future Modules
Example 2: Fluid-structure interaction FSIsolver FluidSolver StructureSolver MeshMover
VISTA Extrud3D
Extruded Products Building industries Automotive industry
The Extrusion Press Ram Container Billet Die holder Profile Die
Flat Strip: Measurement points P1 3 5 6 T3 Die 15 4 T2 Sharp inlet 1 Slip T1 Profile
Mathematical Formulation The Extrusion Problem Governing Equations Boundary Value Problems The Extrusion Solver
Extrusion Problem - The Domain
Governing Equations Heat conduction: non-newtonian fluid: Zener-Hollomon material model
Extrusion Problem - Boundary Value Problem Coupling through temperature dependent viscosity Coupling through deformation energy Coupling through advection
Extrusion Problem - Boundary Value Problem (cont d)
Extrusion Problem - Weak Formulation
Extrusion Problem - Weak Formulation (cont d)
Extrusion Problem - Linearized Fluid Flow Equations
Extrusion Problem - Linearized Fluid Flow Equations (cont d)
Extrusion Problem - Computer Implementation
Extrusion Problem - Model Parameter
Flat Strip: 2D-mesh Container Detail Die Ram Billet (Aluminium) Number of elements = 504 Profile
Flat Strip: 3D-mesh Solve for temperature T Grids do not necessarily match Solve for velocity u pressure p temperature T
Bearing Channel Full stick Slip point Friction Full slip Viscoplastic
Comparison with Experiments Extrusion of a Flat Strip Temperature measurements Aluminum Die Both 2D and 3D analyses B 1 5 A 6 6 T T 9 3 T 2 4 1 7 8. 5 P 1 T 4 3 1. 7 B A
Finite Element Model Full 3D-model Close up Mesh Temperature
Extrusion Problem - The Solver
Flat Strip: Temperature t = 4.4 s t = 16.7 s
Flat Strip: Velocity t = 11.9 s t = 16.7 s
Flat Strip: Temperatures in T1 620 600 580 y T1 T4 z x TEMPERATURE IN T1 ( C) 560 540 520 500 T1_v09_480_stick T1alu_v09_480_exp 480 460 rampos(mm) 0 20 40 60 80 100 120
Flat Strip: Temperatures in T2 500 490 480 y T3d T2d z TEMPERATURE IN T2 ( C) x 470 460 450 T2_v09_480_stick T2die_v09_480_exp 440 430 420 rampos(mm) 0 20 40 60 80 100 120
Thank you for attention!
Feature List Incompressible flow Stokes/Navier-Stokes 2D/3D stationary and time dependent variable density Turbulence modeling LES (Smagorinsky with van Driest damping) RANS (k-e: High Reynolds model) Reference system and boundary conditions ALE formulation Moving object (FSI) Free surface Periodic boundary conditions General boundary conditions (Dirichlet/Neumann) Numerical approximation (Mixed) finite elements (Taylor-Hood, equal order) Continuos projection method (including incremental pressure formulation) Semi-implicit BDF time discretisation Parallel Krylov solver reconditioned with two-level domain ecomposition Software issues Usage Object-oriented (c++) code based on Diffpack Platform independent (running on Unix/Linux) Parallelised with MPI Preprocessor: GRIDDLER Postprocessor: GLview, VTK, Matlab (2D) NTNU/SINTEF: Free usage for education and research
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inutech - Our R&D Experience Differential Equations inutech develops and and markets the the Diffpack Product Line Linefor for the the Numerical Modeling and and Solution of of Differential Equations inutech offers Consulting Services around Diffpack; we we can can deliver customized turn-key solutions for for specialized simulation problems Attention: Diffpack is is a development environment, not not a program! It It allows you you to to generate a simulator!
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The Diffpack Vision (cont d) Structural mechanics Porous media flow Water waves FEM FDM I/O Grid Field Aerodynamics Electro magnetics Observation: Methodology basis independent of applications Heat transfer Vector Matrix Ax=b Other PDE applications Incompressible flow
Diffpack Implementation - use weak formulation [ κ u] f in = Ω u = g on Ω solve on operator level Use weak formulation m κ N N dω + u = f N dω, i = 1,..., m in Ω u = g on Ω j i j i j= 1 Ω Ω
Diffpack Implementation - important member global_menu.multipleloop (S) FEM::makeSystem S::adm S::define S::scan FEM::calcElmMatVec FEM::numItgOverElm S::solveProblem S::integrands S::resultReport
ConvDiff:: integrands (numerical kernel) m k N N dω+ j i j= 1 Ω Ω Au α=0 v N jnidω u Weak Formulation ( ): j = = Ω f N dω, i = 1,..., m i b
ConvDiff :: fillessbc (apply essential boundary Conditions) Apply Boundary Conditions: u ( x, y) = 0, x, y Γ 1 essential conditions