CFD Best Practices & Key Features

Computational Fluid Dynamics

-Key Features & Best Practices

This webinar will be available afterwards at

www.designworldonline.com

Q&A at the end of the presentation

Hashtag for this webinar: #CFDweb

Before We Start

http://www.designworldonline.com/

Moderator

Laura Carrabine Design World

David Kan COMSOL

Presenters

Derrek Cooper Autodesk

Wim Slagter ANSYS

Ivo Weinhold Mentor Graphics

Computation Fluid Dynamics –

ANSYS Software Key Features

and Best Practices

Wim Slagter

Lead Product Manager, ANSYS, Inc.

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ANSYS, the company • ANSYS design, develops, markets

and globally supports a comprehensive range of engineering simulation software

• Proven software technologies for

o Fluid Dynamics

o Structural Mechanics

o Acoustics

o Electromagnetics

o Multiphysics

• Specialized tools, incl.

o ANSYS Icepak (thermal/flow for electronics)

o ANSYS nCode DesignLife (for fatigue)

• World’s largest pool of experts providing CFD Best Practices

Emag

Acoustics

Structural

CAD Import

Parametric Simulation

Design Exploration

Meshing

Post-processing

Fluid

ANSYS – addressing your current & future CFD challenges

Transient or steady-state Laminar and turbulent flows

Heat transfer

Buoyant flows

Incompressible / compressible

Multi-component flows, multi-phase

Real gas modeling

Filters/porous regions Reactions and combustion

Moving geometry and mesh

Rotating machinery

Solution-based adaptive remeshing

1-way and 2-way Fluid-Structure Interaction Courtesy of GE Energy

Courtesy of BMW AG

Key Enablers:

• Links to almost any CAD system

• Parametric, persistent process

• Simulation focused: allows

engineers to do simulation driven

product development

• Direct modeling allows for re-

animating dumb CAD (geometry

without parameters) models

• Extensive modeling solutions

Engineering Productivity: Geometry Modeling

Bi-directional CAD connections

Feature-Based Modeling

Direct Modeling

CAD Neutral: Direct and

Feature-Based Modeling!

Setup Wizards

Engineering Productivity: Workflow

Geometry

Meshing

Problem Setup

Post Processing

Customized Menus

Increased Productivity through

Automation and Customization!

• Advanced physical models

• High-performance solvers

Engineering Productivity: Accuracy & Speed

User-defined LES for highest accuracy;

RANS for all other areas

RANS

LES Re=395

New steady-state scheme as accurate as transient Wigley hull simulation

Free surface profiles

• Steady-state scheme

• Transient scheme

• Experiment

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1.0

0.0 0.5 1.0 1.5

Cavitation number

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Hofmann et al [20]

CFD

Recondisation simulation Cavitating flow in a centrifugal pump can also be modeled in steady state

Get reliable answers faster,

without compromise on flow physics!

Integrated Design Exploration & Optimization

Tradeoff Chart

Parametric CAD model

Response Surface and Sensitivity Chart

Section

Length

Guide

Curve

Angle

Guide

Curve

Radius

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ve

Flo

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Section Length

DOE generated with Design Points

Guide Curve Angle (Deg)

Guide Curve Radius

(mm)

Section Length (mm)

EFA (mm2)

Baseline 63 41 51 1100.2

Optimized 50 30 60.5 1180.4

Baseline Design Optimized Design

Gain deep insights necessary to

optimize product performance, and

produce better products faster!

Drag sensitivity

Downforce sensitivity

Total pressure drop sensitivity

Total pressure drop sensitivity

Estimated downforce improvement = 41.6N

Actual downforce improvement = 39.1N

Adjoint flow solver:

• An understanding of the shape sensitivities with respect to design variables

in a single computation!

• A quantitative performance estimate due to a design change without the

need to simulate the actual change!

Adjoint is a very efficient means of

quickly exploring a design space with

thousands degrees of design freedom!

Shape Sensitivities wrt Design Variables

Fluid Flow

Thermal Stress

Fluid-Structure Interaction

Rigid Body FSI 1-way FSI 2-way FSI

Deformation

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Comprehensive suite of FSI

capabilities for accurate prediction of

a broad range of design scenarios

• Design objective: o Maximize amplification ratio for a given size and power consumption

o 3 main design parameters, i.e. gap in annular ring, internal profile of ring, profile of external ramp

• Customer benefits include: o Explored 10-fold of design variations than would otherwise have been

possible (each day 10 instead of 1)

o Improved performance 250% over original design

Customer Example: Dyson Air Multiplier™ Fan

Courtesy of Dyson

• Design objective: o To optimize the dual-outlet exhaust manifold for robust performance

o 4 main design parameters, i.e. outlet diameter of the manifold, thickness at inlet, external temperature, engine RPM

• Design constraint: o Maximum displacement should not exceed 1.5 mm!

Customer Example: Exhaust Manifold

Fluid Flow

Deformation

Von Mises Stress

Temperature

All samples report maximum deformation

below 1.5 mm

Effect of engine speed and thickness at outlet on

maximum deformation

www.ansys.com

THANK YOU!

http://www.ansys.com/

Enabling engineers to get more done

in 24 hours than any other method-

digital or physical!

Derrek Cooper

Product Manager

Autodesk

Background

• Blue Ridge Numerics, Inc.

• Founded in 1992

• Flagship Product = CFdesign

• Leader in upfront CFD

Enabling Technologies

upfront CFD: Fastest way to solving flow & thermal design challenges!

MCAD Connections

Rules

Materials

CAD Groups

Associativity

Configurations iAssys

Instances Templates



Intelligent Automatic Meshing




Automatic Mesh Sizing

Geometry Mesh

Diagnostics

Automatic Boundary

Layer Meshing

Mesh Refinement

Regions

Automatic Gap

Refinement

Extrusion Meshing

Powerful Advanced

Tools

Solver Technology

AccelerantTM Finite Element

Solver

Accurate FAST

Intelligent Solution Control

Krylov sparse matrix

solver

Auto Convergence Assesment


Unified Design Study Environment

What If! Cloning

Design Review Center

Critical Values

Pass/Fail Summary

Data

Case Study

Lighting manufactures moving to LEDs due to longer life & better performance Challenge- Temperatures must remain lower than traditional lighting The cooler it is, the longer it lasts Rule of thumb – airflow is as important as surface area

Case Study

CFdesign = upfront CFD



MCAD Connections

AccelerantTM Finite Element

Solver

Unified Design Study Environment

Thank you…

David Kan

CFD in COMSOL—Principles

• Ease-of-use

o Tailored functionality and

interfaces

o Robust

• Efficiency

o State-of-the-art performance

o Accurate

• Multiphysics

o Fluid flow with any physics

combination Fluid flow past a solar panel

Tp uuInf

CFD in COMSOL—Technology

• Finite Element Method

• Accuracy

• Stability

• Meshing

• Compatibility

CFD in COMSOL—Applications

Reactor with free and porous flow

regions

Journal bearing

Inkjet

CFD in COMSOL—Results

Gianluca Argentini of Riello Burners in Legnago, Italy

Thank you!

Dr. Ivo Weinhold

Mentor Graphics Corporation

Mechanical Analysis Division

FloEFD Concurrent CFD Embedded in the Design Process

© Mentor Graphics Corp. 2011 – v2.0

Physical Modeling: Advanced Radiation Model

• Radiation is one of the three fundamental methods of heat transfer

• A radiation model must consider the complex physics involved in radiative heat transfer

• Correct radiation simulation is essential for the correct prediction of the temperature distribution in many designs

• Radiation plays an important role for simulations of fluid flow and heat transfer in automotive, building design, electronics cooling, and many more

Advanced Radiation Model

Physical Modeling: Advanced Radiation Model

Advanced Radiation Model

• Radiation absorption in solids

• Wavelength dependency

• Spectrum definition

• Specularity of surfaces

• Refractive index

Physical Modeling: Cavitation Model

• Cavitation describes the process of vaporisation, bubble generation and bubble implosion in a flowing liquid as a result of a decrease and subsequent increase in pressure if the pressure declines to some point below the saturated vapor pressure of the liquid.

• It can occur in control valves, pumps, propellers, impellers, etc.

• The shock waves formed by cavitation are strong enough to significantly damage moving parts. Therefore cavitation is usually an undesired effect.

• Cavitation is a major field in the study of fluid dynamics.

Cavitation Model

Source: Wikipedia

Physical Modeling: Cavitation Model

FloEFD includes two cavitation modeling approaches:

• Engineering cavitation model (for water only):

• This model employs a homogeneous equilibrium approach and has the capability to account for thermal effects.

• Isothermal cavitation model:

• This model is based on the approach considering isothermal two-phase flows for user-defined incompressible liquids.

Cavitation Model

Reference: Wesley, H. B., and Spyros, A. K.: Experimental and computational investigation of sheet cavitation on a hydrofoil. Presented at the 2nd Joint ASME/JSME Fluid Engineering Conference & ASME/EALA 6th International Conference on Laser Anemometry. The Westin Resort, Hilton Head Island, SC, USA August 13 - 18, 1995

Solver Technology: Numerical Schemes

Numerical Schemes • Cell centered finite volume method

• Unified implicit method for both incompressible and compressible liquids and slightly compressible gas flows; Explicit method for high Mach number flows

• Coupled solver for momentum equations

• Conjugate formulation for heat transfer calculation in fluid and solid

• Second order scheme for approximation of conservation laws in fluid and solid

• Monotonic scheme for incompressible tasks

• Multigrid method for linear algebra solver

• CPU time per cell and iteration is independent from cell count

Solver Technology: Mesh Generation

Mesh Generation

• Automatic meshing of fluid and solid regions

• Immersed Boundary Cartesian mesh technology

• Automatic mesh refinement/unrefinement due to geometrical and/or physical (solution adaptive) requirements

• Special cost-effective treatment of thin solids and thin channels

• Automatic immersed boundary treatment (near-wall physics)

AEG Electric Tools - Angle Grinder

Customer Example: AEG Electric Tools – Angle Grinder

Design Challenge:

• Optimize housing openings for cooling performance, dust protection and safety requirements

Benefits:

• The new design protects the motors from abrasive dust while the optimized airflow prevents dust accumulation in sensitive areas such as the switch and electronics.

• It guarantees a better cooling effect – all of which lead to an up to 10 times longer tool lifetime than competitive angle grinders with metal dust chambers.

Customer Example: AEG Electric Tools – Angle Grinder

www.mentor.com

Questions? Design World Laura Carrabine [email protected] @wtwh_laurac

ANSYS Wim Slagter

[email protected]

COMSOL David Kan [email protected] Phone: 310.441.4800

Autodesk Derrek Cooper [email protected] Phone: 215.717.7265 Twitter: @derrekcooper LinkedIn: .../in/derrekcooper

Mentor Graphics Ivo Weinhold [email protected]

mailto:[email protected]

../../../../Downloads/ANSYS CFD_Slagter_final.zip




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