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Full-Text Articles in Engineering
Augmenting External Surface Pressures’ Predictions On Isolated Low-Rise Buildings Using Cfd Simulations, Md Faiaz Khaled, Aly Mousaad Aly
Augmenting External Surface Pressures’ Predictions On Isolated Low-Rise Buildings Using Cfd Simulations, Md Faiaz Khaled, Aly Mousaad Aly
Faculty Publications
The aim of this paper is to enhance the accuracy of predicting time-averaged external surface pressures on low-rise buildings by utilizing Computational Fluid Dynamics (CFD) simulations. To achieve this, benchmark studies of the Silsoe cube and the Texas Tech University (TTU) experimental building are employed for comparison with simulation results. The paper is structured into three main sections. In the initial part, an appropriate domain size is selected based on the precision of mean pressure coefficients on the windward face of the cube, utilizing Reynolds Averaged Navier-Stokes (RANS) turbulence models. Subsequently, recommendations regarding the optimal computational domain size for an …
Jet Noise Reduction: A Fresh Start, Christopher K. Tam, Fang Q. Hu
Jet Noise Reduction: A Fresh Start, Christopher K. Tam, Fang Q. Hu
Mathematics & Statistics Faculty Publications
Attempts to reduce jet noise began some 70 years ago. In the literature, there have been many publications written on this topic. By now, it is common knowledge that jet noise consists of a number of components. They possess different spectral and radiation characteristics and are generated by different mechanisms. It appears then that one may aim at the suppression of the noise of a single component instead of trying to reduce jet noise overall. The objective of the present project is to reduce large turbulence structures noise. It is the most dominant noise component radiating in the downstream direction. …
Streaming Instability With Multiple Dust Species-Ii. Turbulence And Dust-Gas Dynamics At Non-Linear Saturation, Chao-Chin Yang, Zhaohuan Zhu
Streaming Instability With Multiple Dust Species-Ii. Turbulence And Dust-Gas Dynamics At Non-Linear Saturation, Chao-Chin Yang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
The streaming instability is a fundamental process that can drive dust-gas dynamics and ultimately planetesimal formation in protoplanetary discs. As a linear instability, it has been shown that its growth with a distribution of dust sizes can be classified into two distinct regimes, fast-and slow-growth, depending on the dust-size distribution and the total dust-To-gas density ratio . Using numerical simulations of an unstratified disc, we bring three cases in different regimes into non-linear saturation. We find that the saturation states of the two fast-growth cases are similar to its single-species counterparts. The one with maximum dimensionless stopping time τs,max = …
Peak Pressures On Low Rise Buildings: Cfd With Les Versus Full Scale And Wind Tunnel Measurements, Aly Mousaad Aly, Hamzeh Gol-Zaroudi
Peak Pressures On Low Rise Buildings: Cfd With Les Versus Full Scale And Wind Tunnel Measurements, Aly Mousaad Aly, Hamzeh Gol-Zaroudi
Faculty Publications
This paper focuses on the processes of wind flow in the atmospheric boundary layer, to produce realistic full-scale pressures for the design of low-rise buildings. CFD with LES turbulence closure is implemented on a scale 1:1 prototype building. A proximity study was executed computationally in CFD with LES that suggests new recommendations on the computational domain size, in front of a building model, apart from common RANS-based guidelines (e.g. COST and AIJ). Our findings suggest a location of the test building, different from existing guidelines, and the inflow boundary proximity influences pressure correlation and reproduction of peak loads. The CFD …
Bubble Pinch-Off In Turbulence, Daniel J. Ruth, Wouter Mostert, Stephane Perrard, Luc Deike
Bubble Pinch-Off In Turbulence, Daniel J. Ruth, Wouter Mostert, Stephane Perrard, Luc Deike
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Although bubble pinch-off is an archetype of a dynamical system evolving toward a singularity, it has always been described in idealized theoretical and experimental conditions. Here, we consider bubble pinch-off in a turbulent flow representative of natural conditions in the presence of strong and random perturbations, combining laboratory experiments, numerical simulations, and theoretical modeling. We show that the turbulence sets the initial conditions for pinch-off, namely the initial bubble shape and flow field, but after the pinch-off starts, the turbulent time at the neck scale becomes much slower than the pinching dynamics: The turbulence freezes. We show that the average …
Low Level Turbulence Detection For Airport, Derek Kearney, Anthony O'Connor
Low Level Turbulence Detection For Airport, Derek Kearney, Anthony O'Connor
Articles
Low level wind shear and turbulence present a serious safety risk to aircraft during the approach, landing and take-off phases. Despite many advances in on-board and ground based warning systems. Wind shear remains a formidable force that coupled with a microburst can overpower any aircraft. Aviation reports have concluded that pilots need to have improved information in relation to tailwinds, wind shear and wind variations on approach and during the landing phases. Low level wind shear continues to cause disruption, delays and contribute to aircraft crashes. As recently as 2016, two Boeing aircraft crashed while attempting a Go-around manoeuver after …
Experimental Investigation Of Blowing Effects On Turbulent Flow Over A Rough Surface, Mark A. Miller, Alexandre Martin, Sean C. C. Bailey
Experimental Investigation Of Blowing Effects On Turbulent Flow Over A Rough Surface, Mark A. Miller, Alexandre Martin, Sean C. C. Bailey
Mechanical Engineering Faculty Publications
A high Reynolds number turbulent channel flow facility was used to study the combined effects of roughness and flow injection on the mean flow and turbulence characteristics. It was found that the additional momentum injection through the surface enhanced the roughness effects and for the mean flow the effect of blowing was indistinguishable from that of increased roughness. However, for the turbulence statistics, this analogy broke down in that the addition of blowing resulted in behavior which did not follow that predicted by Townsend’s hypothesis. This was observed as a reduction of outer-scaled Reynolds stress well into the outer layer. …
Computational And Experimental Investigation Of The Flow Structure And Vortex Dynamics In The Wake Of A Formula 1 Tire, John Axerio, Gianluca Iaccarino, Emin Issakhanian, Chris Elkins, John Eaton
Computational And Experimental Investigation Of The Flow Structure And Vortex Dynamics In The Wake Of A Formula 1 Tire, John Axerio, Gianluca Iaccarino, Emin Issakhanian, Chris Elkins, John Eaton
Mechanical Engineering Faculty Works
The flowfield around a 60% scale stationary Formula 1 tire in contact with the ground in a closed wind tunnel was examined experimentally in order to assess the accuracy of different turbulence modeling techniques. The results of steady RANS and Large Eddy Simulation (LES) were compared with PIV data, which was obtained within the same project. The far wake structure behind the wheel was dominated by two strong counter-rotating vortices. The locations of the vortex cores, extracted from the LES and PIV data as well as computed using different RANS models, showed that the LES predictions are closest to the …
System For Boundary Layer Control Through Pulsed Heating Of A Strip Heater, Milton E. Franke, Lawrence Kudelka
System For Boundary Layer Control Through Pulsed Heating Of A Strip Heater, Milton E. Franke, Lawrence Kudelka
AFIT Patents
A system is described for controlling the transition of laminar/turbulent flow at a surface which comprises a thin narrow strip heater disposed adjacent the surface and extending substantially transversely of the flow of the air stream thereacross, the heater being resiliently held in tension on or in closely spaced relationship to the surface, and a power source operatively connected to the heater for applying pulsed voltage of preselected amplitude and frequency to the heater.