Edward F. Blick

Bio: Edward F. Blick is an academic researcher from University of Oklahoma. The author has contributed to research in topics: Turbulence & Boundary layer. The author has an hindex of 11, co-authored 31 publications receiving 309 citations. Previous affiliations of Edward F. Blick include Henry Ford Hospital.

Turbulent Boundary-Layer Characteristics of Compliant Surfaces

Abstract: A hot-wire anemometer study was made of the turbulent boundary layer on a compliant coating. A compliant coated flat plate was made by covering a y^-in.-deep reservoir of fluid with a thin sheet of poly vinyl chloride. This compliant test plate which measured 26^ in. X 8^ in. was inserted flush in the floor of a low-speed wind tunnel. The hot-wire anemometer was used to measure velocity profiles, Reynolds stresses and turbulence intensity in the boundary layer. All tests were run at 38 fps and the skin tension, skin thickness, and reservoir fluid properties were varied during the tests. The universal velocity profile of the compliant coating indicated no change in mixing length from that of a hard plate but seemed to indicate a thicker laminar sublayer. The Reynolds stress and turbulence intensity were smaller for the compliant coating than for the hard plate and they seemed to correlate with previously measured skin-friction reductions.

The hydrodynamic stability of flow over Kramer-type compliant surfaces. Part 1. Tollmien-Schlichting instabilities

Abstract: The hydrodynamic stability of flows over Kramer-type compliant surfaces is studied. Two main types of instability are considered. First, there are those which could not exist without viscosity, termed Tollmien–Schlichting Type Instabilities (TSI). Secondly, there are Flow-Induced Surface Instabilities (FISI), that depend fundamentally on surface flexibility and could exist with an inviscid fluid flow. Part 1, the present paper, deals mainly with the first type. The original Kramer experiments and the various subsequent attempts to confirm his results are reviewed, together with experimental studies of transition in flows over compliant surfaces and theoretical work concerned with the hydrodynamic stability of such flows.The Kramer-type compliant surface is assumed to be an elastic plate supported by springs which are modelled by an elastic foundation. It is also assumed that the plate is backed by a viscous fluid substrate having, in general, a density and viscosity different from the mainstream fluid. The motion of the substrate fluid is assumed to be unaffected by the presence of the springs and is determined by solving the linearized Navier–Stokes equations. The visco-elastic properties of the plate and springs are taken into account approximately by using a complex elastic modulus which leads to complex flexural rigidity and spring stiffness. Values for the various parameters characterizing the surface properties are estimated for the actual Kramer coatings.The boundary-layer stability problem for a flexible surface is formulated in a similar way to that of Landahl (1962) whereby the boundary condition at the surface is expressed in terms of an equality between the surface and boundary-layer admittances. This form of the boundary condition is exploited to develop an approximate theory which determines whether a particular change to the mechanical properties of the surface will be stabilizing or destabilizing with respect to the TSI. It is shown that a reduction in flexural rigidity and spring stiffness, an increase in plate mass, and the presence of an inviscid fluid substrate are all stabilizing, whereas viscous and visco-elastic damping are destabilizing.Numerical solutions to the Orr–Sommerfeld equation are also obtained. Apart from Kramer-type compliant surfaces, solutions are also presented for the rigid wall, for the spring-backed tensioned membrane with damping, previously considered by Landahl & Kaplan (1965), and for some of the compliant surfaces investigated experimentally by Babenko and his colleagues. The results for the Kramer-type compliant surfaces on the whole confirm the predictions of the simple theory. For a free-stream speed of 18 m/s the introduction of a viscous substrate leads to a complex modal interaction between the TSI and FISI. A single combined unstable mode is formed in the case of highly viscous substrate fluids and in this case increased damping has a stabilizing effect. When the free-stream speed is reduced to 15 m/s the modal interaction no longer occurs. In this case the effects of combined viscous and visco-elastic damping are investigated. It is found that damping tends to have a strong stabilizing effect on the FISI, in the form of travelling-wave flutter, but a weaker destabilizing effect on the TSI. The opposing effects of damping on the two modes of instability forms the basis of a possible explanation for Kramer's empirical observation of an optimum substrate viscosity. Results obtained using the e9 method also indicate that a substantial transition delay is theoretically possible for flows over Kramer's compliant coatings.

Turbulent blood flow in the ascending aorta of humans with normal and diseased aortic valves.

Abstract: Turbulent blood flow may contribute to a variety of pathophysiological effects Because of its postulated importance, this study was undertaken to determine whether turbulent flow does in fact occur in the human body In 15 persons (seven normal, seven aortic valvular disease, one prosthetic aortic valve), point velocity was measured in the ascending aorta with a hot-film anemometer probe In one normal individual with a high cardiac output, turbulent flow occurred above the aortic valve during peak flow which corresponded to a peak Reynolds number of 10,000 In the other six normal subjects (peak Reynolds numbers of 5,700-8,900), flow was highly disturbed during peak ejection Each of the subjects with aortic valvular disease and the subject with a prosthetic aortic valve showed turbulent flow during nearly the entire period of ejection, with Fourier components of velocity of significant magnitude up to 320 Hz (the maximum frequency we could evaluate with the equipment available) The turbulence energy density was higher in subjects with abnormal valves (32-146 ergs/cm3), than in normal subjects (06-29 ergs/cm3) In subjects with aortic stenosis, turbulence was observed throughout the ascending aorta and in the innominate artery In others, the turbulence dissipated more proximally The results of this study indicate that turbulent flow can occur in the ascending aorta of subjects with normal cardiac function; and it occurs consistently in the ascending aorta of individuals with abnormal aortic valves

Drag reduction in nature

Abstract: Recent studies on the drag-reducing shapes, structures, and behaviors of swimming and flying animals are reviewed, with an emphasis on potential analogs in vehicle design. Consideration is given to form drag reduction (turbulent flow, vortex generation, mass transfer, and adaptations for body-intersection regions), skin-friction drag reduction (polymers, surfactants, and bubbles as surface 'additives'), reduction of the drag due to lift, drag-reduction studies on porpoises, and drag-reducing animal behavior (e.g., leaping out of the water by porpoises). The need for further research is stressed.

Review of Dolphin Hydrodynamics and Swimming Performance

Abstract: : The principal objective of this project was to preform a comprehensive review of performance, kinematics, and swimming hydrodynamics by dolphins and other cetaceans. This report describes information obtained from the available literature including published research and technical reports from English-speaking and Russian sources. The project team specifically studied routine and maximum swimming speeds, morphological design related to hydrodynamic performance, drag reduction, swimming kinematics, thrust production and efficiency, behavior strategies employed for energy