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Multiphysics

Altair is the industry leader in multiphysics simulation with broad and comprehensive software solutions across a wide range of physics including the application of multidisciplinary optimization.

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Tanker Truck Sloshing Simulation Using CFD and Multi-Body Dynamics Solvers The following paper presents a multiphysics analysis of a simplified tanker truck undergoing a lane change maneuver. Bi-directionally coupled CFD and MBD solvers are used to compute the response of the vehicle during a lane change maneuver. Read the White Paper
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Altair’s Solutions for Best in Class NVH Design Process at Automotive OEMs This workshop introduced Altair full frequency and multi-physics solutions for solving the most pressing problems in the NVH field. View the ATC 2015 Presentation
Altair Smart Multiphysics enables best-in-class solutions for solving complex multidisciplinary and multiphysics analysis and design problems involving combinations of physical phenomena including structures, fluids, temperature, multibody systems, acoustics, controls, hydraulics and electromagnetics. All solutions are intended to be used in the design of complex products and are therefore tightly integrated with multidisciplinary optimization.

Built on a single, open architecture multiphysics platform, Altair Smart Multiphysics maximizes the quality, robustness and scalability coming from required single physics solutions of Altair and Altair’s valuable partners, while applying the best coupling and optimization technology to solve complex and real world engineering problems, quickly and effectively.

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“In the past most of the dynamic analysis were done by testing or contracted out. Now with the use of HyperCrash the dynamic analysis can be simulated to reflect real world testing.”

–Spencer Ashie-Winns, Structural Engineering Manager

American Railcar


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Optimization-enabled multiphysics Fluid-structure interaction System simulation and controls Aeroacoustics with NVH Heat transfer and structure analysis Linear and non-linear contact Cable coupling simulation with FEKO Crash and impact analysis (Courtesy of Dallara Automobili)
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Fluid-Structure Interaction

Fluid-Structure Interaction (FSI) involves simulating the behavior of fluids (gas or liquid) and structures as well as mechanical systems simultaneously including how the behavior of one affects the other. Examples would be a wind turbine blade in an air flow, an air plane landing on water, the inflation of an airbag, or tank sloshing. HyperWorks enables engineers to thoroughly study fluid-structure interaction and design for it through different solutions.

RADIOSS provides several solutions for fluid-structure interaction. Using explicit time integration primarily short term events can be simulated. Methodologies include Coupled Eulerian Lagrangian (CEL), Arbitrary Lagrangian-Eulerian (ALE), Smoothed Particle Hydrodynamics (SPH), as well as Finite Volume Method (FVM). Latter is implemented in the context of airbag simulation. Examples include air plane diching, airbag inflation, and bird strike.

AcuSolve is primarily a general purpose Computational Fluid Dynamics (CFD) solver. Thru code coupling it is able to solve FSI problems. This is one of the major strengths of AcuSolve.

AcuSolve offers two types of coupling with a structure.

  • The first technique is called practical FSI (P-FSI). This utilizes a modal reduction of the structure. The methodology works just like component mode synthesis in structures and multibody simulation. The structure is reduced in the modal space and coupled to the fluid domain thru interface nodes. Structural behavior is limited to be linear. Examples are wind turbine blades, rise vortex induced vibrations, and shock absorbers.

  • The second technique is a direct coupling (D-FSI). AcuSolve’s code coupling interface enables easy interaction with other solvers. The coupling is a co-simulation where both AcuSolve and the coupled solver step thru time and iterate to equilibrium in each time step. Within Altair solvers, RADIOSS and OptiStruct are coupled with AcuSolve. Also third-party solvers interfaces have been implemented. Examples include: Offshore oil pipeline motion, aircraft wing/rudder simulation, flow in blood vessels, and race car wing aerodynamics.

Another interesting application of Direct FSI is the coupling of CFD and multibody simulation via coupling AcuSolve with MotionSolve. Initial projects include tank sloshing and a car lane change in a wind tunnel.

System Simulation & Controls

Simulation using three-dimensional modeling is not the only way of understanding physics and designing products. So-called 1D simulation is used to a large extent in product design. This includes physics-based modeling for example using mass, springs, and dampers to model a mechanical system as well as signal-based modeling, for example controls.

The unique offering of Altair technology is the availability of 3D and 1D simulation under one roof. Complex systems can be modeled using both simulation techniques. The VisSim suite of software products can be coupled with Altair 3D solvers. This way a co-simulation environment is available. One of the most obvious use cases is the coupling of controls with multibody simulation. This can be accomplished with Altair MotionSolve, where a MotionSolve model can be included in a Vissim SIMULATE block diagram.

Examples for such simulations are:

  • Control of flight of a drone

  • Engine controls

  • Airplane autopilots

Of course such co-simulation can also be performed using 3rd party control simulation software. The interfaces are available.

Co-simulation is also useful in coupling controls with 3D finite-element solvers. For example controls can be coupled with AcuSolve thru a user-defined function. An example is the climate control in a car that can be simulated and designed.

ChassisSim is multibody vehicle dynamics software that allows race teams and vehicle dynamics engineer to simulate all aspects of vehicle behavior well before the car turns a wheel.

MotionSolve & DSHplus - DSHplus is used to provide the resulting hydraulic forces and control of the movement, while MotionSolve is used to provide displacement and velocity information.

Flexible Bodies

In Computer-Aided Engineering (CAE) accuracy as well as simulation efficiency are important. One method to reduce computational effort without losing much accuracy is to represent deformable structures in a reduced form. Mostly such reduction is done via transformation of the structure into modal space, or by static reduction, or a combination of the two. There is different terminology for this procedure. Flexible bodies, super-elements, practical fluid-structure interaction, component mode synthesis, etc. are all synonymous and depend on context. Let’s call them here flexible bodies as is common in multibody simulation.

OptiStruct is frequently used for the generation of these flexible bodies. Depending on the application they can be use indifferent simulations: in MotionSolve for multibody dynamics, in OptiStruct as a super-element technique for static and dynamic simulations, in AcuSolve for practical fluid-structure interaction, in RADIOSS to linearly reduce parts of the structure. OptiStruct flexible bodies are also compatible with a number of partner and third party applications.

Examples include:

  • Fluid-structure interaction

  • Automotive suspension and closures components

  • Aircraft wing deflection

  • Full body NVH

  • Combustion engine simulation

Aeroacoustics

Computational Aeroacoustics (CAA) represents simulation of sound initiation and propagation based on fluid flow on or around a surface. This discipline requires simulation tools for both the sound initiation as well as sound propagation. Typically, these tools are separate. Therefore a simulation to obtain initial sound pressures is performed with CFD followed by a noise propagation simulation to calculate final sound pressures downstream.

AcuSolve, a general purpose Computational Fluid Dynamics (CFD) solver, can be used to perform calculations for initial sound pressures due to airflow around an object. AcuFWH, an aeroacoustics solver within AcuSolve, is used to simulate sound propagation using the initial pressures calculated from AcuSolve CFD simulation. Altair OptiStruct can then be further employed to study the structural response.

Altair RADIOSS also includes CAA capabilities using Arbitrary Lagrangian-Eulerian (ALE) method. An example is the airflow over an obstacle to study the nose generated by the air.

OptiStruct & Coustyx - By coupling Coustyx with OptiStruct, users are able to calculate noise transmission from a vehicle’s exterior to the interior through the window panel. Noise Radiation Prediction can also be performed by calculating the noise radiated from the powertrain housing.

Examples of aeroacoustics include:

  • Drivers ear noise in automotive

  • HVAC noise

  • Landing gear induced noise

  • Whistle phenomena

Thermomechanical Simulation

Thermomechanical simulation captures deformation and stresses in solids based on the combined effect of mechanical loading and thermal loading, including the coupling due to thermal expansion. Altair’s structural analysis solver OptiStruct has the capability to solve both the thermal and mechanical physics in a single simulation. This enables engineers to understand how a structure behaves based on loading from both the mechanical domain and thermal domains.

Examples of Structural-Thermal applications:

  • Engine manifolds

  • Circuit components

  • Aircraft engine components

  • Satellites/spacecraft

  • Construction/mining equipment

ElectroFlo from TES is an electronics cooling package designed for high power density applications. It is a thermal analysis software that combines the power of coupled thermal/electrical analysis with the ease-of-use of an object oriented Graphical User Interface.

OptiStruct & JMAG - This coupling enables engineers to study the electromagnetic effects on the structural and thermal behavior of systems. By transferring the electromagnetic forces and losses from JMAG to OptiStruct, vibration noise within electrical equipment can be assessed and minimized.

TAITherm from ThermoAnalytics is a thermal simulation tool for comprehensive CAE analysis of both steady state and transient heat transfer conditions. TAITherm has a complete temperature distribution and heat rates for radiation, conduction, and convection.

TESuite from TES is a complete thermal modeling and simulation software, providing the capability to include detailed 3D models of selected sub-systems in an overall system model constructed using a true variable-fidelity approach.

ThermoFlo from TES is a thermal and fluid flow analysis software package which uses a 1D Systems modeling approach, allowing the user to use a component based approach rather than creating a full 3D model.

Fluid Dynamic & Thermal Simulation

Fluid dynamic & thermal simulation involves the simultaneous calculation of fluid flow and fluid temperatures. Many engineering problems require the understanding of how both flow and temperature behave over a given time period. Altair’s AcuSolve CFD solver enables engineers to obtain an understanding of both fluid flow and temperature behavior of the fluid simultaneously.

AcuSolve & JMAG - The JMAG and AcuSolve interface takes the electromagnetic losses from JMAG and maps them as heat sources in AcuSolve for a subsequent thermal/flow analysis.

AcuSolve & TAITherm - Couple TAITherm with AcuSolve to design advanced vehicle cabins based on human comfort, not air temperature.

Examples of CFD-Thermal applications:

  • Electronic circuit thermal management

  • HVAC systems

  • Engine cooling

  • Lighting thermal management

Complementary Solutions

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RADIOSS Leading structural analysis solver for highly non-linear problems under dynamic loadings like Crash, Impact, Blast and Stamping simulation. Overview Video | Learn More
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AcuSolve Leading general-purpose Computational Fluid Dynamics (CFD) solver that is capable of solving the most demanding industrial and scientific applications. Robust and scalable solver technology empowers users by providing unparalleled accuracy. Overview Video | Learn More
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FEKO FEKO is an electromagnetic analysis software suite allowing users to solve a range of electromagnetic problems in realistic operating environments. Overview Video | Learn More
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MotionSolve Integrated solution to analyze and optimize multi-body system performance. Through extensive customer partnership, MotionSolve is thoroughly validated for quality, robustness and speed. Learn More
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