材料数值模拟基础（朱鸣芳）lbmsoftwares

1、introduction of lbm software1 powerflowlei brief introductionpowerflow delivers a revolutionary solution for simulating some of the world's most complex fluid flow problems. built on unique and inherently transient lattice boltzmann technology, powerflow simulations accurately predict real-world

2、 flow conditions without compromising geometric detail. with immersive grid technology, fluid grid creation is completely automatic and captures all the details of geometry, no matter how complex. powerflows unconditional stability means get results every time.using the powerflow suite, engineers ev

3、aluate product performance early in the design process prior to any prototype being builtwhen the impact of change is most significant for design and budgets.1.2 capabilitypowerflow unique technology enables truly predictive simulations of complex flow problems to be performed early in the design pr

4、ocess, when product details are still flexible and expensive prototypes are not available for physical experiments. using actual, unsimplified design geometry, models can be quickly built, simulated and analyzed to deliver concrete answers to design and performance questions. inherently transient an

5、d unconditionally stable, powerflow simulations provide reliable, actionable results every time.powerflowfs capabilities include the following:1) true rotating geometrypowerflow ability to simulate true rotating geometry enables practical and accurate prediction of transient fluid flow around rotati

6、ng components, including prediction of fan noise-something not possible using standard rotating reference frame models. other applications include: fan noise & performance: simulations for axial flow fans centrifugal fans, mixed flow fans and cross flow fans; ability to analyze flow rates, noise

7、 generation, pressure rise. brake cooling wheel aerodynamics pumps, blowers, turbines, mixers2) fast, automated setup with powercasepowercase provides an intuitive, fast interface for preparing cases with any level of geometric complexity. since powerflow fluid grid generation is fully automatic, bu

8、ilding a case is a simple process of creating and importing geometry, defining initial conditions and boundary conditions, and choosing which measurements to record during simulation, a powerful template facility is available to streamline setup of even the most complex cases, and dozens of other ca

9、pabilities streamline the setup process: import and position tessellated geometry from powerdelta or cad systems in stl and nastran formats. create and position simple geometry to complement imported geometry. integrated setup for coupled powercool and powertherm simulations. built-in equation langu

10、age for defining complex time- and space-varying boundary conditions. detect and warn of common setup mistakes.3) digital wind tunnelfor external flow studies, powerflow comes with ready-to-use parametric digital wind tunnel templates. these templates allow cases to be prepared using your own best p

11、ractices in less than an hour from surface mesh files. they can be customized to conform to your wind tunnel: static and moving ground plane modeling to more accurately reflect real world conditions boundary layer suction point to match experimental wind tunnels specification of a known experimental

12、 boundary layer inlet profile4) coupled simulationspowerflow seamlessly couples with complementary exa products to perform expanded simulation capabilities: powertherm : predicts surface temperatures and heat fluxes generated with fully coupled state-of-the-art radiation and conduction solver powerc

13、ool : predicts heat exchanger performance and top tank temperatures with fully coupled cooling system simulation model poweracoustics : aeroacoustic noise prediction and analysis1.3 solution sequence1) simulation preparation powerdelta : meshing & morphing powercase : providing an intuitive, fas

14、t interface for preparing cases with any level of geometric complexity2) simulation powerflow : predicting real-world flow conditions powertherm : thermal management sloution powercool : measuring heat exchanges & cooling airflow3) simulation analysis powerviz : providing fast, interactive visua

15、lization of even the largest data sets，and offers the ability to easily combine different visualization techniques all within the same scene 一 to explore your simulation data as never before. poweracoustics : flow-induced noise analysis powerinsight : streamlining and automating the simulation resul

16、ts generation, analysis and reporting processseulanonpreparay6zresetsseul±onfig.l the diagram of the simulation-based design process1>4 applications1) aerodynamics : aerodynamic efficiency; vehicle handling; soiling and waiter management; panel deformation; driving dynamics2) aeroacoustics :

17、 greenhouse wind noise; underbody wind noise; gap/seal noise; mirror, whistle and tonal noise; sunroof and window buffeting; pass-by/community noise; cooling fan noise3) thermal management : cooling airflow; thermal protection; brake cooling; drive cycle simulation; key-off and soak; electronics and

18、 battery cooling; roa/intake ports4) climate control : cabin comfort; hvac unit & distribution system performance; hvac system and fan noise; defrost and demist5) powertrain : drivetrain cooling; exhaust systems; cooling jacket; engine block1.5 examples1) aerodynamic simulation of racecar.powerf

19、low fits into the rapidly changing environment of racing by providing a broad range of data and flow visualization, which can be used to tune the vehicle design for optimal performance.fig.2 powerflow aerodynamic simulation of tatuus racecar2) brake cooling.the combination of powerflow and powerther

20、m provides a complete thermal analysis, including all three heat transfer modes, and enables you to accurately predict temperatures and visualize the flow and temperature fields for the brake system.fig.3 the flow and temperature fields for the brake system3) panel deformation.powerflow is inherentl

21、y transient, easily and accurately predicting surface pressure fluctuations causing vibrations and the static loads, thus providing a predictive capability to address panel deformation problems. static and transient loads are coupled with your choice of structural solver to compute vibration, static

22、 deformation, and seal performance.fig.4 deformation contours for door and window panels2. xflow2.1 brief introductionin the traditional mesh-based cfd (computational fluid dynamics) approach, the reliability highly depends on the quality of the mesh, and the discretization is a very time-consuming

23、task. furthermore, there are severe difficulties in dealing with the changes in the topology of the domain for problems involving the presence of moving parts or fluid-structure interaction.xflow is a next generation cfd software system that uses a proprietary, particle-based, meshless approach with

24、 the lattice boltzmann method (lbm), which can easily handle traditionally complex problems. xflow is specifically designed for companies who require accurate feedback on flow simulation, transient aerodynamics, water management and fluid-structureinteraction. the xflow approach to cfd simplifies th

25、e workflow, minimizes the presence of algorithmic parameters and avoids the traditionally time consuming meshing process.2.2 capabilityxflow is capable of analyzing flow, thermal and acoustic behavior. xflow can solve problems involving moving boundaries, free surface and fluid structure interaction

26、 on complex geometric domains. detail features of xflow are as follows:1) solver fully lagrangian kinetic solver - lattice boltzmann method compressible transient 2d / 3d single phase flow: internal / external (virtual wind tunnel) free surface flow: internal /external (water channel) multiphase flo

27、w: two immiscible fluids / continuous phase + discrete phase (dpm) heat transfer: conduction / convection / surface-to-surface radiation(monte-carlo) buoyancy (boussinesq approximation) turbulent flow 一 large eddy simulation (les) subgrid-scale turbulence model: smagorinsky / dynamic smagorinsky / w

28、all-adapting local-eddy acoustics 一 direct computation of sound non-newtonian fluids - viscosity models: herschel-bulkley / power-law / cross / carreau / user-defined fluid state-equations: incompressible / ideal gas / boussinesq model2) fluid structure interaction (fsi) rigid body solver fully coup

29、led with fluid solver body motion: 6 dof / constrained / enforced body forces: restitution / friction / external automatic collision detection conjugate heat transfer structural analysis: xflow engine3) boundary conditions wall models: no-slip / free slip / turbulent boundary layer / universal wall

30、model inlet: velocity / mass flow / gauge total pressure outlet: gauge pressure / convective / velocity / mass flow / gauge total pressure others: fan model / porous jump / porous volume / periodicity thermal analysis: adiabatic / temperature / heat flux / conjugate heat transfer / surface emissivit

31、y2.3 solution sequencethe steps for simulating a fluid dynamics problem in xflow are as follows: create the geometry or import it from a cad file check geometry quality and orientation, heal if needed set the problem parameters and the solver options launch the calculation post-process the results2.

32、4 applications1) external aerodynamicsthe virtual wind tunnel module in xflow makes it possible to run full-scale external aerodynamics simulations. the solver is able to compute aerodynamic loads over complex geometry, including the effect of rotating wheels and moving parts. it is possible to anal

33、yze overtaking or dynamic systems such as the vehicle suspension.2) aeroacousticsin order to optimize the acoustic radiation of fan modules, virtual analysis of noise prediction are performed during development. while doing so, the change of geometry can be estimated immediately. the xflow solver op

34、erates at acoustic time scale solving simultaneously the aerodynamics and the acoustic pressure wave propogation.3) water managementxflow is able to simulate free surface problems such as the refueling process, sloshing in the fuel tank, splashing of the wheels on a wet road or driving through water

35、4) discrete phase modelin addition to solving the transport equations for the continuous phase, xflow allows the user to simulate a discrete phase in a lagrangian frame of reference. this discrete phase consists of particles (which may represent droplets, hail, dust, bubbles, etc.) dispersed in the

36、continuous phase, perfectly suited for colloidal flows or soiling applications.5) hvacthe thermal solver can be applied to the simulation of the heating, ventilation, and air conditioning system in a vehicle cabin. fans can be modeled either as rotating parts or using surface boundary conditions. it

37、 is possible to analyze the interior airflow, measure temperature at different locations, and even calculate the passive scalar transport of substances.2.5 examples1) vehicle aerodynamicsxflow is used to observe the three-dimensional air flow around a reference vehicle, instead of the virtual wind t

38、unnel. the vorticity field on the vehicle surface is visualized. other quantics such as velocity, static pressure or turbulence intensity are also can be extracted after calculatons, which provide meaningful insight about the flow.fig.5 isosurface of vorticity around the vehicle surface2) wind turbinethe flow around a wind turbine and its aeroacoustics analysis are im