50 years of Computational Wind Engineering: Past, present and future

Numerical simulations of impinging jets with application to downbursts

Characteristics of thunderstorms relevant to the wind loading of structures

This paper attempts a state-of-the-art summary of research into thunderstorm wind fields from an engineering perspective. The characteristics of thunderstorms and the two extreme wind events-tornadoes and downbursts-spawn by thunderstorms are described. The significant differences from traditional boundary layer flows are highlighted. The importance of thunderstorm gusts in the worldwide database of extreme wind events is established. Physical simulations of tornadoes and downbursts are described and discussed leading to the recommendation that Wind Engineering needs to focus more resources on the fundamental issue - What is the flow structure in the strongest winds? © 2002 Published by Elsevier Science Ltd.

Thunderstorms - their importance in Wind Engineering (A case for the next generation wind tunnel)

Scale, boundary and inlet condition effects on impinging jets

Various types of impinging jet flows are analytically modeled using inviscidfree Gaussian jet solutions superimposed with experimentally fitted boundary layer models. Improved (more robust) and simplified solutions to existing models are defined. Velocity profiles, surface pressure distributions, and streamline plots are calculated for circular, plane, and annular impinging jets. The models show excellent agreement with existing experimental results in both laminar and turbulent conditions and for different Reynolds numbers.

Analytical Solutions for a Family of Gaussian Impinging Jets

An inviscid tornadolike vortex is analytically modeled using a free narrow jet solution combined with a modified Rankine vortex. An empirical and simplified solution to existing models is defined for flows similar to the ones simulated in Ward-type vortex chambers. Velocity profiles are calculated for a particular swirl ratio S r =0.28. The model shows reasonable agreement with existing experimental measurements by Baker (1981, "Boundary Layers in Laminar Vortex Flows," Ph.D. thesis, Purdue University, West Lafayette, IN) and the numerical simulation by Wilson and Rotunno (1986, "Numerical Simulation of a Laminar End-Wall Vortex and Boundary Layer," Phys. Fluids, 29(12), pp. 3993-4005).

An Inviscid Solution for Modeling of Tornadolike Vortices

Experiments were performed to characterize the development of the large-scale structures in the stagnation and wall-jet regions of a turbulent impinging jet with a nozzle-to-plate spacing of 2 diameters and a Reynolds number of 20000. In particular, the instantaneous pressure was measured at 137 points on the wall using 6 concentric rings of pressure taps located 0.25, 0.5, 1.0, 1.5, 2.0 and 2.5 pipe diameters from the jet centreline. The 6 rings respectively contained 8, 16, 16, 32, 32 and 32 equally spaced taps as well as a single pressure tap placed at the jet centerline. The fluctuating pressure was decomposed into azimuthal modes and it was found that a significant portion of the field was contained in azimuthal mode 0 associated with the axisymmetric ring structures and azimuthal mode 1, often associated with jet precessing. The instantaneous pressure was filtered so that only azimuthal modes 0, 1 and −1 remained, and the dynamics of the large-scale structures associated with these modes was examined. These structures were found to be convected radially outward, were highly intermittent, and found to not rotate in a preferred direction.Copyright © 2003 by ASME

Zhuyun Xu

Papers

Scale, boundary and inlet condition effects on impinging jets

Analytical Solutions for a Family of Gaussian Impinging Jets

An Inviscid Solution for Modeling of Tornadolike Vortices

The Dynamics of the Large-Scale Turbulent Structures in the Impinging Round Jet