An improved particle tracking algorithm based on unstructured grids and hybrid grids with arbitrary polygon faces is presented.A dummy triangulation of non-planar polygon faces is carried out as tracking particles across arbitrary hybrid cell faces.Feasibility and reliability are shown through numerical examples.cpu time of the algorithm is compared with that of two algorithms introduced by Haselbacher et al for particles spray into a fixed chamber.The speed up can reach as high as 47% for 10000 particle tracking.

A joint-scalar probability density function (PDF) method, a steady laminar flamelet model, a Eulerian unsteady laminar flamelet model and a hybrid RANS and PDF method are employed in calculating a bluff-body stabilized turbulent non-premixed Sydney flame HM1. Nitrogen oxides emission is numerically simulated with the joint-scalar PDF method and the Eulerian unsteady laminar flamelet model in order to investigate influence of combustion models on the formation of nitrogen oxides. Comparisons between numerical results and experimental data show that chemical reactions by PDF are best while the computational cost is expensive. The laminar flamelet model results shows lower computational cost and are reasonable in complete combustion.

An algorithm with unstructured girds is introduced in which coupling of density and temperature is considered.Static enthalpy equation is employed to construct relation between temperature correction and pressure correction.As in Rhie-Chow method,temperature and pressure corrections of grid interfaces are interpolated by static enthalpy equation and omitting neighbour temperature correction as in the velocity-pressure coupling in SIMPLEC.CGNS is taken as I/O in the in-house unstructured FVM code.For combustion simulation,Arrinius-Eddy dissipation model is employed.

A joint-scalar probability density function (PDF) model is used to simulate bluff-body stabilized turbulent non-premixed Sydney flames HM1. In Situ Adaptive Tabulation (ISAT) algorithm is used to accelerate chemistry calculations. A modified LRR-IP Reynolds stress model is applied to obtain mean flow and turbulent mixing fields. We consider three chemical kinetical schemes for methane chemistry. Simulation results are compared with experimental data. It shows that the model and mechanisms predict flow field, scalar field and local extinction well. C2 chemistry has minor effect on flame HM1.

Based on a one-dimensional laminar reactive flow model,a new pseudo-homogeneous model is constructed and adopted in quasi-steady-state simulation of low-velocity filtration combustion in a packed bed under fully developed conditions.Influences of dispersion effect and reaction mechanisms are discussed in detail by comparsion of the conventional two-phase model with the pseudo-homogeneous model.Effects of various transport terms on different conservation equations are studied.The performance of quasi-steady-state and transient analytical solutions is evaluated by comparing with pseudo-homogeneous model.

An unstructured hybrid grid computational method is proposed,in which CGNS API(CFD General Notation System Application Programming Interface) is taken as pre- and post-processing and FVM(Finite Volume Method) is taken as a PDE(Partial Differential Equation) solver.In the pre-processing,the interior mesh faces and boundary mesh faces are indexed with hash table method for the requirment of the FVM solver.The results of the solver are written into original CGNS files with which the post-processing is dealt with by post-processing softwares,such as tecplot,fluent and CFX.For the solver,a cell centered FVM is applied to solve the coupled pressure and velocities with the SIMPLEC(Semi Implicit Method for Pressure Linked Equation Consistent).Two numerical examples are shown.

CH₄/Air premixed combustion within a two-layer porous medium burner is numerically simulated in a laminar combustion model.Heat exchanges with radiation in the solid and with convection between the gas and the solid are considered.A detailed reaction mechanism GRI 3.0 is used and a dispersion formula is added to the equations.The stabilization of the flame and the emission output are investigated.The results are compared with those of a one-layer burner.It is concluded that a two-layer burner has wider flux range in stabilizing the flame nearby the two-layer porous medium interface.

A consistent hybrid FV/MC algorithm developed on triangular unstructured meshes is implemented to simulate turbulent diffusion flame stabilized on bluff body. Monte Carlo method is used to solve joint fluctuating velocity-frequency-composition PDF equation, while Reynolds averaged mass, momentum and energy equations are solved by finite volume method. The coupling between the two methods reduces the statistical and bias error of stand-alone particle method, so accuracy and efficiency are improved greatly. Laminar flamelet model is incorporated. The simulation results are compared with the experimental data.

Based on the physical model and the calculating method developed by the authors, the calculation software of the spatial distribution of density of x-ray photons in solid is made. The scattering of electron beam with energy in KeV in solid and the excitement of x-ray photons can be simulated by using this program. The quantitative results-of the distributionof density of x-ray photons and the spatial range including various proportion of the photons are also obtained. It is significant for quantitative research of electron microscopy.

Based on the physical model and the calculation method proposed in references[1,2] by anthors,a calculation program of XQMA of micre-particle specimens by using Monte Carlo simulation was made.A series of theoretical formulae for the electron scattering and the production, absorption and fluorescence of characteristic X-rays in particles were given.The datum documents are established in the program.The softwa-re has the ability of automatically treating data,and it can also be applied to the XQMA of block specimens and thin film specimens.