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What is CFD?

Computational Fluid Dynamics commonly referred to as CFD allows engineers to predict fluid flow, heat transfer, mass transfer, and chemical reactions in three dimensions. These phenomena are numerically modeled by a set of partial differential equations called the Navier-Stokes equations.

How did CFD evolve?

In 1960s, CFD was introduced as a specialized engineering tool in the aerospace and defense industries in aerodynamic and hydrodynamic processes. In 1970s CFD expanded its root into the automotive industries in the fluid transmission system. In consequent years, CFD was widely accepted as a common tool in other commercial applications such as semiconductor, MEMS processing and Biomedical etc.

Recently, CFD is integrated into the Computer Aided Design (CAD) environment to perform fluid flow analysis and design analysis in the initial stages of product / process development. With simplification and better integration with the CAD interface, the traditional professionals only CFD is making its way into the mainstream Computer Aided Engineering (CAE) market.

What are the uses and benefits of CFD?

Companies use CFD as a strategic competitive advantage tool to leverage new product and process development, existing process optimization and cost reduction.

The key benefits of CFD are:

Cost:

Developing physical prototypes are extremely costly to build and test. CFD is a valuable tool to assess different designs, perform parametric studies and virtual prototype each design before actual fabrication

Time-to Market: 

CFD identifies the flow and design problem early in the design cycle and reduces the design and development time without compromising on the quality.

Competitive Product Design:

CFD analysis is a significant tool to evaluate multiple what-if scenarios and to iterate the process virtually upon improvement till the optimal design is achieved.

What are the steps in CFD?

The three basic steps CFD modeling are pre-processing, solver, post-processing.

Pre-processing:

The first and foremost step in CFD simulation is creating and gridding a geometry model.  The size and type of mesh elements depends on geometry of model and physical phenomena of interest. While our general purpose pre-processor CFD-GEOM grids the geometry quickly and efficiently, our next generation meshing tool CFD-VisCART is powerful in handling complex geometries such as underhood thermal management studies. Both of these pre-processors support CAD files and SAT, IGES, NASTRAN, PLOT3D, STL files and meshed geometry files such as ICEM-CFD and GAMBIT.  Whether the geometry is an imported CAD model or a meshed geometry, the pre-processors discretize the solution field and locate boundary and volume conditions.

Solver and Solution Generation:

The meshed file is imported into the CFD solver for problem set-up and solution generation. ESI Group has three key solvers for specific simulation needs: CFD-ACE+, CFD-FASTRAN, CFD-CADalyzer.  CFD-ACE+ is a multiphysics and multidisciplinary CFD code that ensure the most efficient operation, both in terms of physics interaction and numerical stability. CFD-FASTRAN is the leading commercial CFD software for aerodynamic and aerothermodynamic applications. It employs state-of-the-art multiple moving body capability for simulating most complex aerospace problems. CFD-CADalyzer is a Coupled Design Analysis CDA tool. It lets design engineers to rapidly and accurately validate their designs earlier in the product development cycle.

Post-processing:

Once the simulation is completed, the native simulation file is imported into the post-processing software which allows the user to visualize and analyze the results. ESI group post processor CFD-VIEW provides an easy-to-use and interactive environment with many graphics tools to visualize the flow physics, animate transient data sets, as well as extract data relevant to engineering design. CFD-VIEW also supports Tecplot files Ensight files etc.

What is Multiphysics

Multiphysics is the process of simulating the effects of two or more interacting physical Phenomena. Multiphysics typically involve solving coupled systems of partial differential equations. From catheters to semiconductor processing and from microphones to MEMS (microelectromechanical systems), many of today’s design challenges require evaluating more than one aspect of physics that are coupled, and often mutually dependent, phenomena.

The more common and mature analyses of multi physics include fluid–structure, thermal–mechanical, and electric–thermal interactions. In fluid–structure interaction, fluid flow exerts pressure on a solid structure, which causes it to deform such that it perturbs the initial flow. Example: Deformation of an aircraft wing during flight. In Thermal– mechanical many structures change their shapes and material properties as a result of a temperature increase or decrease. Example: Transient heating of an automotive exhaust manifold due to flow of the internal hot exhaust gas stream. In Electric-thermal interaction, current flowing in a conductor generates resistive heating. Example: Heat conduction in dielectric and semiconductor material.

CAD

Acronym for Computer-Aided Design. CAD is a computer package that is used to aid the design and development of products.

CAE

Acronym for Computer-Aided Engineering. CAE are the computer system that can simulate and analyze design under a variety of conditions to see if it actually works. 

CAM

Acronym for Computer-Aided Manufacturing. Software solution for manufacturing products.

CFD

Acronym for Computational Fluid Dynamics. Computational Fluid Dynamics commonly referred to as CFD allows engineers to predict fluid flow, heat transfer, mass transfer, and chemical reactions in three dimensions. These phenomena are numerically modeled by a set of partial differential equations called the Navier-Stokes equations. The CFD code from ESI Group offers unique capabilities for Multiphysics, Multiscale, and Coupled Simulations of fluid, thermal, chemical, biological, electrical, and mechanical phenomena for real-world applications.

Collaborative Workspace

An interconnected environment in which all the participants of a project can electronically access and interact with each other’s work-in-process designs. This shared environment yield a way to improve communication and enhance productivity among the product development team. ESI Group’s Virtual Try Out Space (VTOS) is built based on this concept.

CRM

Acronym for Customer Relationship Management. CRM is the systematic collection and utilization of business data in order to understand and analyze the interests of customers and compare that with the company’s products and services offerings and to make informed decisions.

DEM

Acronym for Discrete Element Modeling. Discrete element method (DEM) is a technique where the mechanics of thousands of interacting, individual elements are computed. It handles problem that could not be solved by the continuum procedure like Finite Element Method.

DES

Acronym for Detached Eddy Simulation. DES is a recent technique, devised to predict separated flows at high Reynolds numbers with a manageable cost. DES contains a single model, typically with one transport equation, which functions as a RANS model in the boundary layer and as a Sub-Grid-Scale model in separated regions, where the simulation becomes an LES.

DNS

Acronym for Direct Numerical Simulation. DNS is the most accurate way to study numerically a turbulent flow. In this approach the flow field in solved directly from the Navier-Stokes equations and no averaging or turbulence modeling is applied. Thus only the numerical methods affect the accuracy of the solution. DNS is especially well suited for turbulent studies and combustion-related phenomena. DNS is computationally intensive and currently only feasible for simple flows at low Reynolds Numbers.

FEA

Acronym for Finite Element Analysis. Finite Element Analysis is a computer simulation technique used in engineering analysis. It uses a numerical technique called the finite element method (FEM). The common use of FEA is for the determination of stresses and displacements in mechanical objects and systems. However, it is also routinely used in the analysis of many other types of problems, including those in heat transfer, fluid dynamics and electromagnetism. FEA is able to handle complex systems that defy closed-form analytical solutions.

FEM

Acronym for Finite Element Method. In numerical analysis, the finite element method (FEM) is used for solving partial differential equations (PDE) approximately. Solutions are approximated by either eliminating the differential equation completely (steady state problems), or rendering the PDE into an equivalent ordinary differential equation, which is then solved using standard techniques such as finite differences, etc.

FVM

Acronym for Finite Volume Method. The finite volume method is a method for representing and evaluating partial differential equations as algebraic equations. It calculates the values of the conserved variables averaged across the volume. Finite volume methods are especially powerful on coarse nonuniform grids and in calculations where the mesh moves to track interfaces or shocks.

FSI

Acronym for Fluid-structure interaction. FSI is the fully coupled solution of fluid flows with structural interactions. The typical ESI Group’s FSI applications are in aeroelastic applications, MEMS and Biomedical.

IGES

Acronym for Initial Graphics Exchange Specification. IGES is universally accepted neutral file format used to translate geometrical information between different CAD, CAE and analysis software packages. Visit www.nist.gov/iges/ for details.

LES

Acronym for Large Eddy Simulation. LES is a compromise between DNS and RANS. LES seeks to directly solve large spatial scales (like DNS), while modeling the smaller scales (RANS).  The basis for this is two-part.  First, the larger scales carry the majority of the energy, and hence are more important.  Second, the smaller scales have been found to be more universal, and hence are more easily modeled.  The resulting methodology is a hybrid between these two methods, which involves the filtering of the Navier-Stokes equations to separate those scales which will be modeled from those which will be solved for directly. LES is valuable for predicting flow involving flow separation and aeroacoustic flows.

Multiphysics 

Multiphysics is the process of simulating the effects of two or more interacting physical phenomena. Multiphysics typically involve solving coupled systems of partial differential equations.

PLM

Acronym for Product Lifecycle Management. It is the process of managing the entire lifecycle of a product from its conception, through design and manufacture, to service and disposal. PLM is a set of capabilities that enable an enterprise to effectively and efficiently innovate and manage its products and related services throughout the entire business lifecycle.

RANS

Acronym for Reynolds-averaged Navier-Stokes equations. It is the oldest approach to turbulence modeling. In addition to the ensemble version of the governing equations, a new apparent stress called the Reynolds stress is added to the function for solving the time averaged effects of turbulence.

RSM

Acronym for Reynolds Stress Model Reynolds stresses Model. This approach attempts to actually solve transport equations for the Reynolds stresses. This means introduction of several transport equations for all the Reynolds Stresses and hence this approach is much more costly in CPU effort.

STEP

Acronym for Standard for the Exchange of Product Model Data. STEP is a comprehensive ISO standard (ISO 10303) that describes how to represent and exchange digital product information Visit www.steptools.com/library/standard/ for details.

VOF

Acronym for Volume of Fluid/Flow Model. The Volume of Fluid (VOF) method is a Direct Numerical Simulation (DNS) method which helps to perform the simulation of free surface flows. It uses a filling process that determines filled cell and the emptied cell in the meshing volume.

VPD

Acronym for Virtual Product Development. Virtual Product Development  encompasses a wide variety of software tools that take a product design from conception through the beginning of production, helping the engineer to design by trial and error on the computer Virtual product development allows us to recognize and evaluate the characteristics of a product on the basis of a simulation at an early stage without having to build a model.

Virtual Prototyping

Virtual prototyping is the process of using a virtual prototype, in lieu of a physical prototype, for test and evaluation of specific characteristics of a product design.

VTOS

Virtual Try-Out Space is a concept which allows all the company’s solutions to work with each other and with solutions developed by other extended enterprise players. This multi-physical and multi-trade solution allow ‘predictive evaluation’ and ‘continuous online improvement’ of virtual prototypes and processes, helping to optimize decision-making.