Narrow Results

A numerical research of wind loads on straight and twisted towers is presented in this paper. Computational Fluid Dynamics (CFD) method is used to simulate wind action on building. Shear Stress Transport (SST) model is adopted for transient simulations, as a compromise between computational cost and accuracy. Numerical results obtained in this work demonstrate a significant benefit of twisted building in reducing cross wind loads. When wind flows over a straight tower, vortexes form and shed in cycle with a constant frequency in the wake. The resulting cyclic cross wind load will cause significant vibration of building. By twisting a high-rise building the vortex shedding is confused, and hence the harmful cross wind load effects are avoided.

Transient simulation of heat properties for vehicle exhaust system components plays an important role in vehicle development process. Simulation analysis can find thermal materials risk in early stage of project, and quickly give proposal so as to reduce test cost. Based on STAR-CD software, a vehicle exhaust system model, which includes the exhaust gas, the exhaust pipes and aftertreatment devices, was established. A three-dimensional transient simulation was undertaken for the heat properties of vehicle exhaust system components. The heat properties with the periodic pulsating exhaust gas velocity were obtained and analyzed, and the transient mean value were compared with the steady results, the results show the predicted the unsteady mean exhaust gas surface temperatures are higher than 50°C,the unsteady mean surface heat dissipating capacities of exhaust gas system components are 11.3 percent up at the 10% pulsating exhaust gas velocity condition.