A numerical investigation of the effects of crosswinds upon the aerodynamic characteristics of a high-speed passenger train and its slipstream

The main work presented within this thesis is a numerical investigation of the effects of crosswind yaw angles upon the aerodynamic characteristics of a high-speed passenger train. The applicability of Computational Fluid Dynamic (CFD) approaches to the simulation of external flow around a passenger train were investigated. Results showed the Delayed DES (DDES) approach produced the highest correlation to experimental results. Ballast heights of 0m, 0.3m and 0.75m were simulated and compared to existing experimental results. Comparisons between cases found that a vortex from the train’s underbody follows the ballast profile. Crosswind simulations were conducted at yaw angles of 0o, 5o, 10o and 15o. The results obtained showed the formation of a large vortex upon the leeward side at yaw angles of 10o and above, this caused a region of low pressure which increased the overturning forces acting upon the train. Generally, crosswinds increased pressures upon the windward side of the train and decreased them upon the leeward side. Slipstream velocities on the windward side were seen to decrease whilst leeward side velocities increased. Results were compared to regulations currently in place for the operation and testing of trains. This enabled comments and suggestions to be made upon existing regulations

Trains in crosswinds – comparison of full-scale on-train measurements, physical model tests and CFD calculations

In this paper a major series of experiments is described that included extensive full-scale measurements of cross wind induced pressures on the Class 43 New Measurement Train over an extended 21 month period, together with wind tunnel, moving model tests and CFD calculations, and allows, for the first time, a proper evaluation of the adequacy of these techniques. Static wind tunnel tests and moving model tests show good agreement with each other, both in terms of the measured pressure field around the train and in the overall side force per unit length over the yaw angle range from 15 to 30°. Similarly the wind tunnel tests and the CFD calculations show good agreement with each other for yaw angles up to 15°. Two different analyses of the full-scale data were carried out - an analysis of 1 s average wind speeds and forces, and an analysis of specific gusts. There was a very great deal of scatter in the results and only the results from simple track topographies were found to agree well with the model and computational results

Life Sciences Uniting in Assessing Student Writing

Student learning outcome (SLO) statements made by an educational program serve as targets for achievement and openly communicate the knowledge and skills students are expected to acquire from the program. Clearly stated SLOs are the necessary foundation of an evidence-based educational program through which faculty, staff, and student efforts are aligned. Establishment of these statements is, therefore, the primary step in building a robust, cooperative, and effective assessment system for improving student learning and development. Here we discuss an approach to the formulation, adoption, and application of a single SLO for undergraduate writing to be used across the five undergraduate majors (Biology, Marine Biology, Microbiology, Molecular and Cell Biology, and Botany) in the School of Life Sciences formed in Fall 2019 through the merger of the Departments of Biology, Microbiology, and Botany

Comparison of RANS and detached eddy simulation results to wind-tunnel data for the surface pressures upon a class 43 high-speed train

Currently, there are three different methodologies for evaluating the aerodynamics of trains; full-scale measurements, physical modeling using wind-tunnel, and moving train rigs and numerical modeling using computational fluid dynamics (CFD). Moreover, different approaches and turbulence modeling are normally used within the CFD framework. The work in this paper investigates the consistency of two of these methodologies; the wind-tunnel and the CFD by comparing the measured surface pressure with the computed CFD values. The CFD is based on Reynolds-Averaged Navier–Stokes (RANS) turbulence models (five models were used; the Spalart–Allmaras (S–A), k-ε, k-ε re-normalization group (RNG), realizable k-ε, and shear stress transport (SST) k-ω) and two detached eddy simulation (DES) approaches; the standard DES and delayed detached eddy simulation (DDES). This work was carried out as part of a larger project to determine whether the current methods of CFD, model scale and full-scale testing provide consistent results and are able to achieve agreement with each other when used in the measurement of train aerodynamic phenomena. Similar to the wind-tunnel, the CFD approaches were applied to external aerodynamic flow around a 1/25th scale class 43 high-speed tunnel (HST) model. Comparison between the CFD results and wind-tunnel data were conducted using coefficients for surface pressure, measured at the wind-tunnel by pressure taps fitted over the surface of the train in loops. Four different meshes where tested with both the RANS SST k-ω and DDES approaches to form a mesh sensitivity study. The four meshes featured 18, 24, 34, and 52 × 106 cells. A mesh of 34 × 106 cells was found to provide the best balance between accuracy and computational cost. Comparison of the results showed that the DES based approaches; in particular, the DDES approach was best able to replicate the wind-tunnel results within the margin of uncertainty.</jats:p

Birmingham Environment for Academic Research : Case studies volume 2

The work within this case study was brought together to publicise the different types of work that was done on the University’s high performance computer called BlueBEAR2 and on the many systems that help researchers. This computer system is part of the University of Birmingham’s environment for academic research (BEAR), which helps staff and students of the University delve deeper into their research than has been done before. Traditional research has always been to experiment or theorise, BlueBEAR is used to deliver a third option, computer based modeling. Computer based modeling is used to underpin the physical and theoretical research. Sometimes computer based modeling is the only way (e.g. colliding galaxies, nuclear explosions), where safety and cost is prohibitive. This is a small set of case studies taken from the vast research that is being done on BlueBEAR2 and generally around the University. BlueBEAR2 is the next generation of hardware from BlueBEAR and includes large memory, GPGPU, database and data mining services