Sunday, September 15, 2013

Application of CFX module in ANSYS



          ANSYS CFX software is a high-performance, general purpose fluid flow dynamics analysis program that has been applied to solve wide-ranging fluid flow problems. ANSYS CFX is its advanced solver technology, the key to achieving reliable and accurate solutions quickly and robustly. The modern, highly parallelized problem problem solver is that the foundation for an easy selection of physical models to capture virtually any type of phenomena related to fluid flow problem. The solver and its many physical models are wrapped in a trendy, intuitive, and flexible graphical computer programme and user environment, with extensive capabilities for customization and automation using session files, scripting and a powerful expression language.
          But ANSYS CFX is more than simply a robust CFD code. Integration into the ANSYS Workbench platform, provides superior bi-directional connections to all major CAD systems, powerful geometry modification and creation tools with ANSYS DesignModeler, advanced meshing technologies in ANSYS Meshing, and easy drag-and-drop transfer of information and results to share between applications. For example, a fluid flow solution can be used within the definition of a boundary load of a sequent structural mechanics simulation. A native two-way connection to ANSYS structural mechanics product permits capture of even the most sophisticated fluid–structure interaction (FSI) issues among constant easy-to-use atmosphere, saving the need to get, administer or run third-party coupling software.
          The following are some of the foremost important physical models offered in ANSYS CFX software package.

  • Turbulence: The large range of industrial flows are turbulent. Therefore, ANSYS CFX software pay special attention on providing and developing turbulence models to capture the effects of turbulence accurately and with efficiency. In addition to all common RANS models — like k-ε, k-ω, SST and Reynolds-Stress models — and scale resolving LES and DES models, ANSYS CFX software delivers several important turbulence modeling related innovations. These innovations include SST model extensions to calculate effects like streamline curvature, a predictive laminar-to-turbulent transition model (the Menter-Langtry γ−θ model™) and the novel scale-resolving Scale-Adaptive Simulation™ (SAS) model for flows within which steady-state turbulence models are insufficient.
  • Rotating Machinery: ANSYS CFX software has continuously shown leadership in CFD simulation for rotating machinery. It is a frontrunner in a field where the demands in terms of accuracy, speed and robustness are among the very highest. From a full suite of models to capture the interaction between rotating and stationary components, to tailored turbomachinery pre- and post-processing environments, ANSYS CFX software fully satisfies the needs of turbomachinery fluid dynamics analysts. It is further complemented by ANSYS® BladeModeler™ and ANSYS® TurboGrid™, geometry and mesh generation tools created expressly to meet the requirements of turbomachinery designers and analysts.
  • Multiphase: More than twenty years of expertise in multiphase modeling is incorporated into ANSYS CFX code, to allow the simulation of multiple fluid streams, bubbles, droplets, particles and free surface flows. The Lagrangian transport model allows the solution of one or a lot of discrete particle or droplet phases within a continuous fluid phase. Breakup models are offered to describe both the initial fluid atomization and further fragmentation due to the action of external forces. Further choices include an efficient statistical particle-particle collision model and a quasi-static wall film model. The Eulerian multiphase model incorporates a wealth of options to capture the exchange of momentum, energy and mass, including numerous drag and non-drag force models as well as robust models for phase transition because of cavitation, evaporation, condensation and boiling. The multiple size group (MUSIG) model is offered to simulate the breakup and coalescence of disperse phases in poly-dispersed multi-phase flows.
  • Heat Transfer and Radiation: Beyond solving the convective transport of energy by fluid flow, ANSYS CFX software includes a conjugate heat transfer (CHT) capability to solve the thermal conduction in solids. It also incorporates a wealth of models to capture all types of radiative heat exchange in and between fluids and solids, whether these are fully or semitransparent to radiation or opaque.
  • Combustion: Whether simulating combustion design in gas turbines, automotive engines or coal-fired furnaces, or assessing fire safety in and around buildings and other structures, ANSYS CFX software provides a rich framework to model chemical reactions and combustion associated with fluid flow. Combustion models are provided for anything from laminar to turbulent flows, fast to slow chemical kinetics and non- to partially or fully pre-mixed reactants. A rich library of predefined chemical reactions that can be easily edited and extended by users, as well as the integration of the flamelet library generator ANSYS CFX-RIF for detailed chemistry tables, provides a complete range of options for all situations. These are rounded out with models for auto and spark ignition, pollutant formation (NOx, soot), residual exhaust gases, knock, wall quenching, flame extinction and more.
  • Fluid Structure Interaction (FSI): ANSYS combines the specialized capabilities and technology of its leading fluid dynamics and structural mechanics software to provide the most advanced capability for the simulation of the interaction between fluids and solids. Both one-way and two-way FSI simulations are possible, from problem setup to post-processing, all within the ANSYS Workbench environment. The native two-way connection to structural analysis technologies from ANSYS allows users to capture even the most complex FSI problems without the need to purchase, administer or configure third-party coupling software.
  • Moving Mesh, Remeshing and Immersed Solids: Beyond the powerful range of options for capturing FSI together with ANSYS structural analysis technologies many additional options exist directly within ANSYS CFX software to model the effect of solid motion on fluid flow. Mesh deformation technology used in FSI simulations to allow large ranges of motion with a fixed mesh topology can be combined with external remeshing to capture even the most complex geometry movement. This motion can be either prescribed, such as the valve and piston motion in an internal combustion engine, or can be an implicit result of the solution using the built-in six-degrees-of-freedom rigid body solver available in ANSYS CFX software. The immersed solids method is an additional option that allows unlimited motion of solid objects through fluid to be defined without any need for mesh deformation. The collection of strategies available means that ANSYS CFX users have options for virtually every conceivable geometry motion.

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Sunday, September 8, 2013

Application of ANSYS Structural Analysis for Mechanical and Civil Engineering



Analysis on Rim


       Finite Element method (FEM) is most common Numerical Analysis Technique. The most common application of FEM is Structural analysis. The term structural (or structure) define not only in civil engineering structures like Building, flyover and bridges and buildings, but in addition armed service, aeronautical, and mechanical structures such as car, ship hulls, fighter plane, and machine housings, as well as mechanical components like pistons, machine components, and tools.
          The seven types of structural analyses offered in the ANSYS. The primary unknowns (nodal degrees of freedom) evaluated during a structural analysis are displacements. Other quantities, such as strains(diifferent type like von-Mises), stresses, and reaction forces, are then derived from the nodal displacements.
          Structural analyses are available in the ANSYS Multiphysics, ANSYS Mechanical, ANSYS Structural, and ANSYS Professional programs .


  • Static Analysis--It is used to determine deformation, stresses, safety factor contact stress etc. under static loading conditions. Both linear and nonlinear behavior static analyses. Non-linearity can include malleability, stress stiffening, large deflection, large strain, hyper-elasticity, contact surfaces, and creep.
  • Modal Analysis--It is used to calculate the mode shapes and natural frequencies of a structure. Different mode extraction methods are available.
  • Harmonic Analysis--It is used to determine the response of a structure to harmonically frequency time-varying loads.
  • Transient Dynamic Analysis--It is used to determine the response of a structure to arbitrarily (random) time-varying loads. All non-linearity mentioned under Static Analysis above are allowed.
  • Spectrum Analysis--An extension of the modal analysis, used to calculate stresses and strains due to a response spectrum or a PSD input (random vibrations).
  • Buckling Analysis--It is used to calculate the buckling loads in column and determine the buckling mode shape of column. Both linear (eigenvalue) buckling and nonlinear buckling analyses are possible.
  • Explicit Dynamic Analysis--This type of structural analysis is offered within the ANSYS LS-DYNA program only. ANSYS LS-DYNA provides an interface to the LS-DYNA explicit finite element(FE) program. Explicit dynamic analysis is used to calculate fast solutions for large deformation dynamics and complicated contact problems


          A static structural analysis calculates the effects of steady loading conditions on a structure, while ignoring inertia and damping effects, such as those caused by time-varying loads. A static structural analysis can, however, include steady inertia loads (such as gravity and rotational velocity), and time-varying loads that can be approximated as static equivalent loads (such because the static equivalent wind and seismic loads commonly defined in many building codes).
         Static structural analysis determines the displacements, stresses, strains, and forces in structures or components caused by loads that do not induce significant inertia and damping effects. Steady loading and response conditions are assumed; that is, the loads and also the structure's response are assumed to vary slowly with respect to time. The types of loading that will be applied during a static analysis include:

  • Externally applied forces and pressures
  • Steady-state inertial forces (such as gravity or move velocity)
  • Imposed (nonzero) displacements
  • Temperatures (for thermal strain)
  • Fluences (for nuclear swelling)

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