HFSS Hybrid Finite Element and Integral Equation Solver ... · PDF fileHFSS Hybrid Finite...

HFSS Hybrid Finite Element and Integral Equation Solver for large scale electromagnetic design and simulationelectromagnetic design and simulation

Presenter: Andrew Wang

© 2011 ANSYS, Inc. August 26, 20111

AgendaOverview of Simulation Trends and Technologies

ANSYS Simulation Technologies Overview

ANSYS Electromagnetic Simulation Techniques:

HFSS‐FEM

HFSS IE New in v12HFSS‐IE New in v12

Hybrid FE‐BI New in v13

Hybrid IE‐Regions New in v14 Hybrid IE Regions

Physical Optics New in v14

High Performance Computing

HFSS with Domain Decomposition Method (DDM) New in v12

HFSS‐IE with industry standard Message Passing Interface (MPI) New in v14


Examples

Simulation Trends

Full System Simulations• Require simulation of more complicated and electrically large problems

• Efficient simulations• Efficient simulations

Types of problems to solve


ANSYS Technologies Advancing Electrically large Simulation CapabilitiesSimulation Capabilities

HFSS provides access to multiple solver technologies and simulation techniques ll l l l d l bl b l d• Allowing electrical larger and more complex problems to be solved

– Integral Equation: e‐large metallic open‐space models, such as antenna placement, RCS etc

Hybrid FE BI: e large complex material models such as antenna radome system– Hybrid FE‐BI: e‐large complex material models, such as antenna radome system, composite aircraft etc

– IE‐Regions New in v14 : e‐large complex ‘separate’ models, such as reflector antenna, GPR, RCS etc

– Physics Optical New in v14 : e‐large smooth metallic models, mainly for antenna placement, RCS etc

High Performance ComputingHigh Performance Computing• Shared Memory Parallel ‐ Faster

• Distribute Memory Parallel ‐ Larger

– HFSS


HFSS

– HFSS‐IE New in v14

ANSYS Simulation Technologies • Finite Element Method

• HFSS

• Efficiently handles complex material and geometries

V l b d h d fi ld l ti• Volume based mesh and field solutions

• Fields are explicitly solved throughout entire volume

• Integral Equations• HFSS‐IE

• Efficient solution technique for open radiation and scattering

• Currents solved only on surface mesh• Currents solved only on surface mesh

• Efficiency is achieved when structure is primarily metal

• Physical Optics new in v14• Physical Optics new in v14

• HFSS‐IE

• High frequency approximation

• Ideal for electrically large, smooth objects


• Currents are approximated in illuminated regions and set to zero in shadow regions

• 1st order interactions

Hybrid Finite Element – Integral EquationsFE BI

Finite Element Method

FE-BI

• HFSS• Efficiently handles complex

material and geometries

• Hybrid Finite Element ‐ Integral EquationsHybrid Finite Element Integral Equations

• FE‐BI introduced in v13

• IE‐Regions New in v14

H b id h d i k d i id f HFSS D i i• Hybrid method invoked inside of HFSS Design using IE‐Regions or FE‐BI boundary conditions

• Hybrid method takes advantage of features from b h h d ll f ffi i i l i

Integral Equations

• HFSS‐IEboth methods to allow for more efficient simulations

IE-Regions

• Efficient solutiontechnique for open radiating and scattering of metallic objects


High Frequency Technique: Physical OpticsHigh frequency asymptotic solver available inside of

Physical Optics• HFSS‐IE

• Ideal for electrically large

High frequency asymptotic solver available inside of HFSS‐IE designs

• Currents are approximated in illuminated regions and set to zero in shadow regionsIdeal for electrically large,

conducting and smooth objects

zero in shadow regions

• First order interaction only, single bounce

• Source excitation from HFSS Far Field Data‐Link of incident plane wave

Usage• Application include

• Electrically large RCS Antenna Placement Reflector• Electrically large ‐ RCS, Antenna Placement, Reflector Analysis

• Quickly estimate performance of electrically large problems

• Full wave solution is beyond computation resourcesFull wave solution is beyond computation resources


Hybrid MethodsFE‐BI

IE‐Regions


Finite Element‐Boundary IntegralM h t ti f i fi it f i tMesh truncation of infinite free space into a

finite computational domain

• Alternative to ABC or PML radiation boundary conditions

Fields at outer surface

boundary conditions

Hybrid solution of FEM and IE

• IE solution on outer faces

FEM Solution in Volume

IE Solutionon Outer Surface

• FEM solution inside of volume

FE‐BI Advantages

• A bit h d b d

Iterate

• Arbitrary shaped boundary– Conformal and discontinuous to minimize solution

volume

• Reflection less boundary condition

FE-BI

Reflection less boundary condition– High accuracy for radiating and scattering problems

• No theoretical minimum distance from radiator


radiator– Reduce simulation volume and simplify problem

setup

Free space Arbitrary shaped

Finite Element‐Boundary Integral:Boundary Condition Setup

Enabled with HFSS‐IE license feature inside of an HFSS Design

S t i i il t ABC b d ditiSetup is similar to ABC boundary condition

• Enabled by selecting “Model exterior as HFSS‐IE domain”

Radiation surface must enclose entire geometry

• 1 infinite ground plane allowedg p

Direct vs. Iterative Matrix Solver

• Direct Matrix Solverf d h d h– Preferred method with FE‐BI

– Quickest solution

• Iterative solver

© 2011 ANSYS, Inc. August 26, 201110

– Uses the least amount of RAM

Finite Element‐Boundary Integral:Example Problem

FE‐BI can be used to significantly reduce required computer resourcesresources

• Large volume of air inside of radome can be removed from the FEM solution domain– Air volume would be required if using PML or ABC

FE-BI

• Two FE‐BI surfaces will be applied– Conformal to radome

Conformal to horn antenna (10 GHz) Surface– Conformal to horn antenna (10 GHz)

10 GHz RAM (GB) Elapsed Time

ABC 15 70min

© 2011 ANSYS, Inc. August 26, 201111 FE-BIABC

FE‐BI 7 30min

IE‐Regions New in v14 FEM Only Solution

In a hybrid FEM‐IE solution, IE Regions allow uniform regions of free space or dielectric to be removed from the FEMdielectric to be removed from the FEM solution

• Metal objects can be solved directly with an IE solution applied to surfacepp

• Removes need for air box to surround metal objects

• Dielectric regions can be replaced with anHybrid FEM‐IE Solution

IE Region

Dielectric regions can be replaced with an IE Region on the boundary of uniform dielectric material

• Solution inside of dielectric is solved using IE

© 2011 ANSYS, Inc. August 26, 201112 FE-BISurface current on metal block

IE‐Regions:Boundary Condition Setup

IE Solution Applied to Metal outside of air box and dielectric inside of air box

y p

IE‐Regions can be applied to metal or dielectric objects inside of an HFSS Design Metal

Dielectricεr = 4

Design

• Metal Objects

• Typically exterior to air box region with FE‐BI outer radiation boundary orFE BI outer radiation boundary or

• Internal to dielectric IE Region

• Dielectric Objects

b b Air Volume truncated with FE BI• Must be interior to air box regionAssignment:

• Select Object

Air Volume truncated with FE-BI radiation boundary condition

• HFSS IE Regions Assign As IE Region

© 2011 ANSYS, Inc. August 26, 201113

IE‐Regions:Example Problem

Radius = 900mm, Epsr = 4, F = 1GHzExample Problem

IE‐Region Applied to RCS of Electricaly Large Dielectric Sphere

• Hybrid FEM IE solution of scattering from• Hybrid FEM‐IE solution of scattering from dielectric sphere using IE‐Regions

• Uniform volume of dielectric removed by applying IE‐Region to surface of dielectric sphereapplying IE Region to surface of dielectric sphere

IE‐Region applied toFEM Only applied to dielectric Sphere

FEM OnlyHybrid FEB‐IE Solution

FEM Only Hybrid FEM‐IE

1 GHz RAM (GB) Elapsed Time

FEM O l 33 4 222 i

© 2011 ANSYS, Inc. August 26, 201114

FEM Only 33.4 222min

Hybrid FEM‐IE using IE Regions 3.2 35min

10X Less 7X Faster

Hybrid Solution

With the addition of IE regions to HFSS v14 a fully hybridized solution of FEM and IE is capable of more efficient solution to electrically large problemsand IE is capable of more efficient solution to electrically large problems

FEM and IE• FEBI

– Truncate an FEM solution space with any arbitrary surface using a boundary integral

• IE‐Regions

When used along with FE BI conducting objects outside of FEM solution space can– When used along with FE‐BI, conducting objects outside of FEM solution space can be solved directly with IE, eliminating the need for conducting objects to be enclosed in an air volume

– Homogenous dielectric volumes can be removed from the FEM solution and greplaced with the equivalent IE solution in the region, useful when dielectric regions are electrically large requiring large FEM solution volume

© 2011 ANSYS, Inc. August 26, 201115

High Performance Computing Applied to Hybrid MethodsApplied to Hybrid MethodsHPC with HFSS using Domain Decomposition

HPC with HFSS‐IE using MPI New in v14 g

© 2011 ANSYS, Inc. August 26, 201116


Increase simulation capacity using High Performance Computing (HPC)

Domain Decomposition Method (DDM) for HFSS• HFSS only

• HFSS using FE‐BI and IE‐Regions New in v14

Distributed Memory Parallel for HFSS‐IE New in v14

• Uses industry standard Message Passing Interface (MPI)

• Perform HFSS‐IE simulation by distributing solution across machines in a cluster or y gnetwork

© 2011 ANSYS, Inc. August 26, 201117

High Performance Computing with HFSS using DDMusing DDM

• Distributes mesh sub‐domains to network of processors

FEM l b b• FEM volume can be sub‐divided into multiple domains

IE D i th t HPC distributes mesh sub-domains, FEM and discontinuous IE domains, to networked processors and memory

• IE Domains that are discontinuous will be distributed to separate nodes when they becomenodes when they become large

• Significantly increases simulation capacitysimulation capacity

• Multi‐processor nodes can be utilized

© 2011 ANSYS, Inc. August 26, 201118

FEM Domain 1

FEM Domain 2

FEM Domain 3

FEM Domain 4

IE Domain

High Performance Computing with HFSS‐IE i MPIusing MPI

HFSS-IE uses MPI to perform solution distributedt k d tacross networked computers

• The HFSS‐IE solver in HFSS 14 uses the industry standard Message Passing f (“ ”) d f l i h di ibInterface (“MPI”) and can perform solutions that distribute memory use across

machines in a cluster or network

• Simulation capacity is only limited by available computer resources

© 2011 ANSYS, Inc. August 26, 201119

• Enables simulation of electrically large

HFSS v14 Licensing Configurations for El i l L Si l iElectrical Large Simulations

New features in HFSS v14 enabling large scale electromagnetic design and simulationsimulation

Hybrid FEM and IE Solution• FE‐BI and IE‐Regions

HPC Li– Requires HFSS and HFSS‐IE license

Distributed Memory Hybrid HFSS and HFSS‐IE• For Hybrid HFSS and HFSS‐IE

HPC License

DDM– HFSS, HFSS‐IE and HPC License

• For HFSS‐IE Only

– HFSS‐IE and HPC LicenseHFSS License

(FEM)HFSS-IE License

(IE/PO)

Hybrid FEBIIE‐RegionsHFSS to IE/PO

Physical Optics• Requires HFSS‐IE license

(FEM) (IE/PO)Datalink

© 2011 ANSYS, Inc. August 26, 201120

ExamplesFinite Element ‐ Boundary Integraly g

IE‐Region

Physical Optics


© 2011 ANSYS, Inc. August 26, 201121

Array on Spacecraft Using FE‐BI

7 Element Helix Antenna Array integrated on satellite platform

• Dielectric solar panels and antennaDielectric solar panels and antenna supports do not make this problem ideal for HFSS‐IE

Inclusion of solar panels create anInclusion of solar panels create an electrically large model

• 64λ wide at 3.5 GHz

Using ABC or PML boundary wouldUsing ABC or PML boundary would require an Airbox equal to 21k λ3

FE‐BI can reduce the required Airbox to 1.2k λ3

© 2011 ANSYS, Inc. August 26, 201122

FE‐BI applied to conformal Airbox ABC or PML would be applied to much larger Airbox

Array on Spacecraft Using FE‐BI: Results

Array platform integration simulated with conformal FE‐BIwith conformal FE BI

• RAM requirements reduced by 10x

• RAM reduction as a result of removing the surrounding free spacethe surrounding free space– Only possible using FE‐BI

BoundaryType

Airbox Volume

Number of Domains

Total RAM (GB)yp ( )

ABC 21k λ3 34 210

FE‐BI 1.2k λ3 12 21

© 2011 ANSYS, Inc. August 26, 201123

10X Less

Reflector Analysis Using IE‐RegionsMultiple techniques have been developed to analyze reflector antennas using HFSS• Full HFSS Solution ‐Model entire solution space using only HFSS

– High level of fidelity also requires most computer resources

• Data Link Solutions – Source feed excitation modeled separately from reflector

– Data link solutions only include 1 way coupling from source excitation to reflector

• Hybrid Solutions

– Efficient, high fidelity solution using hybrid FEM‐IE techniques

s Full HFSS Solution

Full HFSS solution requires large air box (~37k λ3)

er Resou

rces

Data Link

Full HFSS Solution

Hybrid Solutions

Compu

te IE Solutions

Data LinkPhysical Optics

© 2011 ANSYS, Inc. August 26, 201124

FidelityHybrid Solution uses FEM for feed and IE applied to reflector

Reflector Analysis Using IE‐Regions: SetupAnalysis of electrically large reflector antennas may benefit from multi‐step

design approach utilizing several simulation methodologies Data Link with HFSS

d h i l i

Data LinkFull Wave Solutions

Data LinkPhysical Optics

Feed AntennaDesign

and Physical Optics

Hybrid Solutions

HFSS to HFSS‐IE or PO Data‐link:

• Source excitation solved in HFSS

• Used as data linked excitation into a Physical

Hybrid FEM‐IE Solution

Optics or HFSS‐IE Simulation

FE‐BI (IE‐Region)

• Full wave simulation performed using a h b id l ti i HFSS

© 2011 ANSYS, Inc. August 26, 201125

hybrid solution in HFSS

• IE‐Region Applied to FEM Solution with FE‐BIIE solution on reflector

Reflector Analysis Using IE‐Regions: ResultsF ll l i ibl i h b id FEM IE l i bl d i h

FEM Solution with FE‐BI•Full wave solution possible using hybrid FEM‐IE solution, enabled with FE‐BI and IE‐Regions

•Agreement between methods only show small difference in peak and side lobe levels

Off t f d fl t•Offset fed reflector•Backscatter and blockage not fully included in either data‐linked simulation – effects would be more significant for center fed reflector

Full Wave SolutionHFSS to IE Data‐LinkHFSS to PO Data‐Link

© 2011 ANSYS, Inc. August 26, 201126

IE solution on reflector

Reflector Analysis Using IE‐Regions: Results

Boundary Type Airbox Volume Total RAM (GB) Elapsed Time (hours)

Hybrid FEM‐IE HFSS to PO Data‐LinkHFSS to IE Data‐Link

Full HFSS solution (FEM Only, DDM) 37k λ3 163.5 (1st pass) 2.7 (1st pass)

Full Wave Hybrid FEM‐IE 8.6 λ3 (Feed Only) 5 0.5>32X Less >10X Faster

© 2011 ANSYS, Inc. August 26, 201127

HFSS to IE Data‐Link NA 3.4 0.2

HFSS to PO Data‐Link NA 0.4 1 minute

Hybrid Solution for Antenna Placement Analysis Using IE‐Regions

Antenna performance modeled with placement in proximity to human head

C ll h l f d i h• Cell phone platform and antenna with complex material properties and geometry are ideally modeled using FEM solution

1.8 GHz

solution

• The uniform, high dielectric properties of the head are ideally modeled using IE solutionsolution

Hybrid Solution• An internal dielectric IE Region can be

li d h d dapplied to head geometry to reduce computational size and improve efficiency

• FEM solution is applied remaining

© 2011 ANSYS, Inc. August 26, 201128

• FEM solution is applied remaining volume Human Head Material Properties:

εr= 79, σ= 0.47simems/m

Hybrid Solution for Antenna Placement Analysis Using IE‐Regions: Results

IE‐Region Boundary Condition Applied

Cell Phone OnlyCell Phone OnlyFEM Only: Cell Phone + HeadHybrid: Cell Phone + Head

FEM Only SolutionHybrid FEM‐IE Solution1.8 GHz 1.8 GHz

Solution Type Total RAM (GB) Elapsed Time (hours)

FEM Only 6.2 1

© 2011 ANSYS, Inc. August 26, 201129

Hybrid Solution 3 0.5

2X Faster2X Less

Hybrid Solution for Antenna Placement Analysis Using IE‐Regions

Antenna performance modeled with placement in proximity to human head Inside a BMW car

• Cell phone platform and antenna with complex material properties and geometry are ideally modeled using FEM solutiong

• The uniform, high dielectric properties of the head are ideally modeled using IE solution

• The car is ideally modeled using IE Region

Hybrid Solution Setupy p• An internal dielectric IE Region can be applied to head geometry to reduce computational

size and improve efficiency

• An exterior metallic IE Region is applied to car model

FEM l i i li d i i lFEM solution around body and cell phoneIE sol tion applied to dielectric h man bod• FEM solution is applied remaining volume IE solution applied to dielectric human body using IE‐Regions

© 2011 ANSYS, Inc. August 26, 201130IE solution on car body using IE‐Regions

Hybrid Solution for Antenna Placement Analysis Using IE‐Regions : Results


© 2011 ANSYS, Inc. August 26, 201131

FEM w/ DDM 160G 8

Hybrid Solution 11 2.7

3X Faster15X Less

Hybrid Solution for Antenna Placement Analysis Using IE‐Regions: Resultsg g


Full FEM Solution

160 GB (DDM) 8Solution

3X Faster15X Less

Full FEM Solution

3X Faster15X Less



11 2.7Solution

© 2011 ANSYS, Inc. August 26, 201132


Physical Optics (PO) for Electrically Large SimulationsSimulations

High frequency asymptotic solver

• Scattering and antennaPhysical OpticsFull Wave Solution

• Scattering and antenna placement of electrically large objects

RCS of PEC Sphere

• Highlights capabilities and

Solution @ High Freq. Total RAM (GB) Elapsed Time (sec)

Full Wave (HFSS‐IE) 1.4 87

Physical Optics 0 1 14

limitation of physical optics

• Creeping wave effects not accounted for by PO

Physical Optics 0.1 14

I id t W

• When electrical size of sphere becomes large, full wave solution converges with physical optics

© 2011 ANSYS, Inc. August 26, 201133

Incident Wave

Full Wave Solution Physical Optics Solution

with physical optics solution

Physical Optics for RCS of Electrically L SLarge Structures

0 00

10.00PECRCS_HH ANSOFT

Good correlation between full wave solution and physical optics solution for RCS of electrically l hSphere

30 00

-20.00

-10.00

0.00

1

large cone‐sphere• Creeping wave effects not accounted for in physical optics solution

• Apparent as incident anglesTip

Sphere

-50.00

-40.00

-30.00Y

Physical OpticsFull Wave Solution

• Apparent as incident angles approach tip and sphere side of cone‐sphere

0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00IWavePhi [deg]

-70.00

-60.00

F ll W S l tiFull Wave Solution Physical OpticsSolution @ High

Freq.Total RAM (GB) Elapsed Time

Full Wave (HFSS‐IE) 6.6 2 hours

© 2011 ANSYS, Inc. August 26, 201134Shadow Region

Physical Optics 4.8 16 minutes

International Space Station: Antenna Placement and Blockage Simulationsand Blockage Simulations

Multiple antenna and communication channels operating on and around the ISS are subject to blockage due to the large structureg g•Physical Optics Allows us to model important navigational and communications challenges

•Degradation of communications due to adjusting solar panels on ISS •Blockage of GPS signals used by docking vehicles

110 meters

© 2011 ANSYS, Inc. August 26, 201135

Physical Optics for S‐Band Communications on ISS Antenna Blockageg

733 λ

Solution @ 2GHz Total RAM (GB) Elapsed Time (min)

Physical Optics 47 57

© 2011 ANSYS, Inc. August 26, 201136

Distribute HFSS‐IE Using MPI

Full wave solution using HFSS‐IE of electrically large structures

250λ

electrically large structures

175λ

© 2011 ANSYS, Inc. August 26, 201137

Distributed HFSS‐IE Solution of HARM at 18 GHz

246λ@ 18 GHz

Full wave RCS of HARM at 18 GHz performed using distributed HFSS‐IEHFSS IE

Physical Optics SolutionFull Wave HFSS‐IE Solution

Physical Optics SolutionDistributed HFSS‐IE Solution Resources

Average Memory 8 GB

Total Memory (10 nodes) 80 GB

© 2011 ANSYS, Inc. August 26, 201138


Total Time 7 Hours

Distributed HFSS‐IE Solution: Fighter Aircraft

Full wave solution

Scattering of fighter aircraft at 5GHz

Large scale simulation possible by using compute cluster of 10 networked machines

Solution only possibly using Scatteringy p y gdistributed computing resources

Physical Optics SolutionFull Wave HFSS‐IE Solution

Distributed HFSS‐IE Solution Resources

Average Memory 32 GB


© 2011 ANSYS, Inc. August 26, 201139

Total Time 33.5 Hours

Summary

Data LinkPh i l O ti Ne

ize Data Link

IE Solutions

Physical Optics New in v14

IE Solutions

IE/MPI New in v14 Model M

ade

l Electric Si IE Solutions

F )FEBI (IE-Region New in v14 )FEM/HPC

FEBI/HPC New in v14

aterial Com

Mod

Full HFSS Solution

FEM/HPC

mplexity

Fidelity

© 2011 ANSYS, Inc. August 26, 201140

Special Thanks to Inphi

Inphi LRDIMM test machineInphi LRDIMM test machine– 284GB RAM

© 2011 ANSYS, Inc. August 26, 201141

HFSS Hybrid Finite Element and Integral Equation Solver ... · PDF fileHFSS Hybrid Finite...

Documents

Transcript of HFSS Hybrid Finite Element and Integral Equation Solver ... · PDF fileHFSS Hybrid Finite...