Geometry: shape, size, aspect ratio and orientation Flow Type: forced, natural, laminar, turbulent, internal, external Boundary: isothermal (Tw = constant) or isoflux (q̇w = constant) Fluid Type: viscous oil, water, gases or liquid metals Properties: all properties determined at film temperature Tf = (Tw + T∞)/2 Note: ρ and ν ∝ 1/Patm ⇒ see Q12-40 density: ρ ((kg/m) specific heat: Cp (J/kg ·K) dynamic viscosity: μ, (N · s/m) kinematic viscosity: ν ≡ μ/ρ (m/s) thermal conductivity: k, (W/m ·K) thermal diffusivity: α, ≡ k/(ρ · Cp) (m/s) Prandtl number: Pr, ≡ ν/α (−−) volumetric compressibility: β, (1/K)

Convection Heat Transfer

Patients with vertebral, hip, distal radius, and proximal humerus fractures are most common among the osteoporosis-related fractures. The incidences of these fractures increase with age, however, the increase patterns differ between the fracture sites. The prevalence of vertebral fracture for Japanese is similar or slightly higher and the incidences of osteoporosis-related limb fractures are lower than those for Caucacians. A decrease in prevalence of vertebral fractures and an increase in the incidence of limb fractures are the secular trend in Japan. Previous fractures are significant risk factor for both vertebral and hip fractures. Greater physical activity increases the risk of distal radius fractures, and decreases the risk of proximal humerus fractures.

Epidemiology of osteoporotic fractures

The aerodynamic characteristics of train/vehicles under cross winds depend on not only the shapes of the vehicles but also those of infrastructures. Accordingly three kinds of wind tunnel tests were made to evaluate the aerodynamic characteristics of typical configurations of the vehicles on typical configurations of infrastructures such as bridges and embankments. The main results obtained from the wind tunnel tests are summarized below. 1. The aerodynamic side force coefficient of the vehicle increases more as the thickness of the bridge girder becomes larger. It also increases more as the roof of the vehicle becomes edgier. 2. The aerodynamic characteristics of the vehicle on the embankment depend on the distribution of the boundary layer on the ground. The aerodynamic side force coefficient of the vehicle on a high embankment is larger than that on a low embankment.

Aerodynamic Characteristics of Train/Vehicles under Cross Winds

\n High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.

Review of research on high-speed railway aerodynamics in China

The performance of different turbulence models (URANS, SAS and DES) for predicting high-speed train slipstream

Slipstreams caused by high-speed train movement through the atmosphere pose a safety risk to passengers, trackside workers and track infrastructure. The improved delayed detached eddy simulation (IDDES) approach, an improved version of the detached eddy simulation method, is adopted in this paper to calculate the slipstream of a four-coach 1/25th-scale model of the CRH2 high-speed train. Slipstream velocities and pressures at various lateral distances from the centre of rail (COR) position and vertical distances from the top of rail (TOR) position at trackside are calculated. Numerical results are compared with measurements obtained in a full-scale test and good agreement is obtained, which verifies the effectiveness and potential of the less costly IDDES method. It is found that the velocity and pressure distributions are similar to those obtained using different train types but with different peak values related to the difference in shapes. The peak velocities in the slipstream along the length of the t...

Mingzhi Yang

Papers

Numerical calculation of the slipstream generated by a CRH2 high-speed train:

Experimental study on the effect of wind angles on pressure distribution of train streamlined zone and train aerodynamic forces

Oblique tunnel portal effects on train and tunnel aerodynamics based on moving model tests

Pressure transients induced by a high-speed train passing through a station

Reduction of pressure transients of high-speed train passing through a tunnel by cross-section increase