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This paper seeks to reduce the time it takes to perform external aerodynamic simulations without compromising accuracy. At present, cleaning up CAD data sets, in particular for undercarriage parts, takes several man‐weeks.

Body‐fitted and embedded mesh techniques are combined to obtain accurate external aerodynamic solutions for realistic car geometries with minimal user intervention. The key idea is to mesh with typical body‐fitted RANS grids the external shape of the vehicle, which is smooth and requires detailed physical modeling. The underhood and undercarriage are treated as embedded surfaces. The flow in this region is massively separated, requiring LES runs and isotropic grids. This makes it a suitable candidate for embedded grids.

Comparisons with body‐fitted and experimental data for a typical car show that this approach can yield drag predictions with an error less than 5 percent.

The present approach reduces turnaround times for complete car geometries to one to two days, without compromising accuracy.

To the authors' knowledge, this is the first time such an approach has been tried and validated for external aerodynamics.

A new method of three‐dimensional remeshing is proposed for thermo‐viscoplastic finite element analysis of connecting rod forging. In the method, the deformed body to be remeshed is divided into a surface‐adaptive layer (SAL) and a core region. At the surface layer of hexahedral elements, the arrangement of nodal points is made by normal projection of boundary nodes in order to retard the mesh degeneracy, since the arrangement of boundary nodes can be easily achieved by using the information of the die surface patch. After generating the mesh automatically at the surface‐adaptive layer, the core region is automatically meshed by introducing a body‐fitted mapping technique. In order to show the effectiveness of the method in the three‐dimensional problem, forging of a connecting rod has been simulated as a practical example. The complete simulation of connecting rod forging has been carried out by using the thermo‐viscoplastic finite element method and the remeshing scheme. The analysis of transient heat transfer has been carried out for the workpiece by the finite element method, while the boundary element method has been used for the die.

The purpose of this study is to model the dynamic characteristics of an opened supersonic disk-gap-band parachute.

A fluid-structure interaction (FSI) method with body-fitted mesh is used to simulate the supersonic parachute. The compressible flow is modeled using large-eddy simulation (LES). A contact algorithm based on the penalty function with a virtual contact domain is proposed to solve the negative volume problem of the body-fitted mesh. Automatic unstructured mesh generation and automatic mesh moving schemes are used to handle complex deformations of the canopy.

The opened disk-gap-band parachute is simulated using Mach 2.0, and the simulation results fit well with the wind tunnel test data. It is found that the LES model can successfully predict large-scale turbulent vortex in the flow. This study also demonstrates the capability of the present FSI method as a tool to predict shock oscillation and breathing phenomenon of the canopy.

The contact algorithm based on the penalty function with a virtual contact domain is proposed for the first time. This methodology can be used to solve the negative volume problem of the dynamic mesh in the flow field.

The purpose of this study is to apply the topology and parameter optimization (TPO) to interior permanent magnet (IPM) motors to obtain the optimized shape with higher torque, lower ripple and sufficient mechanical strength.

The constraints regarding the maximum stress, connectivity and mesh quality were considered to achieve not only high electrical performance but also high mechanical strength. To enhance the accuracy of the finite element analysis of the elastic analysis, this paper used body-fitted mesh adaptation technique to avoid the stress concentration.

The proposed method in this study resulted in feasible shapes with sufficiently high strength compared to previous studies. It is also shown that TPO yielded IPM motors with higher torque compared to topology optimization (TO) with fixed parameters.

Different from the existing studies on topology optimization of IPM motors, the mechanical strength is even considered by evaluating the stress values. Therefore, in the practical phase, geometries can be designed that are less likely to be damaged due to deformation, even in the high-speed rotation range.

This paper performed TO and parameter optimization (PO) simultaneously, considering not only the electrical performance but also the mechanical strength. Furthermore, the mechanical strength was evaluated more precisely by devising the elastic analysis conditions and mesh generation.

The problems of transient natural convection from a corrugated plate embedded in an enclosed porous medium is studied numerically. The non‐Darcian effects as well as the acceleration terms are taken into consideration in the momentum equation. The governing equations in terms of vorticity, stream function and temperature are expressed in a body‐fitted coordinates system, which were solved numerically by the finite difference method. Results are presented in terms of streamlines and isotherms, local and average Nusselt numbers, with Darcy‐Rayleigh number ranging from 0 to 1000, and Darcy number from 10^–4 to 10^–1, for several aspect ratios of the cavity and plate positions. The flow and heat transfer characteristics for a corrugated plate and a flat plate and the numerical results solved with four different mathematical models are also compared.

The purpose of this paper is to present two different methods for the imposition of thermal boundary conditions (BCs) in the framework of two-phase flows: an immersed boundary method (IBM) and a Ghost cell method. Both methods are able to handle Dirichlet as well as Neumann BCs.

Direct numerical simulations of two-phase flows are performed where the thermal BCs at the phase boundary is accounted for with two different approaches.

Both methods are validated with the results obtained on a body-fitted mesh. Simulations of the three-dimensional flow and temperature field around a sphere demonstrate versatility and accuracy of both methods.

This is the first time Neumann BCs are imposed by means of an IBM with a direct heating approach employing regularized delta functions. The test cases considered may also serve as benchmarks for other studies.

The purpose of this paper is to report on the flow past a porous square cylinder, implementing the stress jump treatments for the porous‐fluid interface.

The numerical method was developed for flows involving an interface between a homogenous fluid and a porous medium. It is based on the finite volume method with body‐fitted and multi‐block grids. The Brinkman‐Forcheimmer extended model was used to govern the flow in the porous medium region. At its interface, a shear stress jump that includes the inertial effect was imposed, together with a continuity of normal stress.

The present model is validated by comparing with those for the flow around a solid circular cylinder. Results for flow around porous square cylinder are presented with flow configurations for different Darcy number, 10⁻² to 10⁻⁵, porosity from 0.4 to 0.8, and Reynolds number 20 to 250. The flow develops from steady to unsteady periodic vortex shedding state. It was found that the stress jump interface condition can cause flow instability. The first coefficient β has a more noticeable effect whereas the second coefficient β₁ has very small effect, even for Re=200. The effects of the porosity, Darcy number, and Reynolds number on lift and drag coefficients, and the length of circulation zone or shedding period are studied.

The present study implements the numerical method based on finite volume method with a collocated variable arrangement to treat the stress jump condition.

A numerical study is reported of natural convection melting of ice within a vertical cylinder. A stream function‐vorticity‐temperature formulation is employed in conjunction with body‐fitted coordinates for tracking the irregular shape of the timewise varying solid‐liquid interface. A parabolic density profile versus temperature is assumed for water. Numerical experiments are carried out for a temperature of the cylinder wall ranging from 4°C to 10°C. Results show that natural convection heat transfer involving density anomaly leads to complex flow patterns and strongly affects the time evolution of the phase front. The maximum Nusselt number at the heated cylinder wall is obtained for Tw = 4°C while the minimum is observed for Tw = 8°C.

An algorithm based on flux difference splitting is presented for the solution of two‐dimensional, steady, supercritical open channel flows. A transformation maps a non‐rectangular, physical domain into a rectangular one. The governing equations are then the shallow water equations, including terms of slope and friction, in a generalised coordinate system. A regular mesh on a rectangular computational domain can then be employed. The resulting scheme has good jump capturing properties and the advantage of using boundary/body‐fitted meshes. The scheme is applied to a problem of flow in a river whose geometry induces a region of supercritical flow.

The paper aims to report on the flow past a porous trapezoidal‐cylinder, in which the porous‐fluid interface was treated by implementing the stress jump boundary conditions.

The numerical method was based on the finite‐volume method with body‐fitted and multi‐block grids. The Brinkman‐Forcheimmer extended model was used to govern the flow in the porous medium region. At its interface, a shear stress jump that includes the inertial effect was imposed, together with a continuity of normal stress.

The present model was validated by comparing with those for the flow around a solid circular cylinder. Results for flow around porous expanded trapezoidal cylinder are presented with flow configurations for different Darcy number, 10⁻² to 10⁻⁷, porosity from 0.4 to 0.8, and Reynolds number 20 to 200. The flow develops from steady to unsteady periodic vortex shedding state. The first coefficient β has a more noticeable effect, whereas the second coefficient β₁ has very small effect, even for Re   =   200.

The effects of the porosity, Darcy number and Reynolds number on lift and drag coefficients, and the length of circulation zone or shedding period are studied.