Last edited by Akinole
Friday, July 17, 2020 | History

2 edition of Turbulent boundary layer over solid and porous surfaces with small roughness found in the catalog.

Turbulent boundary layer over solid and porous surfaces with small roughness

Fred Y Kong

Turbulent boundary layer over solid and porous surfaces with small roughness

by Fred Y Kong

  • 163 Want to read
  • 16 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch, For sale by the National Technical Information Service] in Washington, D.C, [Springfield, Va .
Written in English

    Subjects:
  • Turbulent boundary layer,
  • Porous materials -- Thermal properties,
  • Frictional resistance (Hydrodynamics)

  • Edition Notes

    StatementFred Y. Kong, Joseph A. Schetz, and Fayette Collier ; prepared for Langley Research Center under grant NAG-1-119
    SeriesNASA contractor report -- 3612
    ContributionsSchetz, Joseph A, Collier, Fayette, Langley Research Center, United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch, Virginia Polytechnic Institute and State University. Aerospace and Ocean Engineering Dept
    The Physical Object
    Paginationx , 78 p. :
    Number of Pages78
    ID Numbers
    Open LibraryOL14931063M

      This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy. The book is devoted to the Buckingham Pi-theorem and its applications to various phenomena in nature and engineering. The accent is made on problems character-istic of heat and mass transfer in solid bodies, as well as in laminar and turbulent flows of liquids and gases. Such choice is not accidental. It is dictated by the.

    The Boundary Layer section asserts that laminar flow over a rough surface has the same convective surface conductance as laminar flow over a smooth plate. Note that when the mean-heigh-of-roughness is larger than the thickness of the viscous-sublayer (but still much less than L c), the flow becomes turbulent and the assertion about laminar. Among the first were Oke () on the urban heat island (UHI), Uno et al. () on the nocturnal urban boundary layer (UBL), and Rotach (a,b) on turbulent vertical profiles in the urban roughness sublayer (URS, from street level up to 50– m).

    Air dehumidifier, Solid Desiccant System, Thermal Performance Air quality, bio-indicator, Dirinaria picta, lichen Airflow control, dielectric barrier discharge (DBD), plasma actuator Airflow, gust, helicopter, lift, main rotor Airfoil noise, Leading edge noise, Leading edge . between a turbulent boundary layer and a porous medium have received much less attention. The exception is the work of de Lemos and Silva (Silva and de Lemos , de Lemos and Silva etc.) who proposed, but without derivation, to extend the stress condition of Ochoa-Tapia and Whitaker by adding turbulent viscosity.


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Turbulent boundary layer over solid and porous surfaces with small roughness by Fred Y Kong Download PDF EPUB FB2

The turbulent boundary layer over a smooth, solid wall is examined along with a sandpaper-roughened, solid wall, and a porous wall.

Suitable results are obtained with the smooth, solid wall for the Law of the Wall, the Defect Law, and the axial and turbulence intensities. The logarithmic portion of the Wall Law is shifted in the sandpaper-roughened, solid wall and an increase in the normal Cited by: 8.

Turbulent boundary layer over solid and porous surfaces with small roughness. Washington, D.C.: National Aeronautics and Space Administration, Scientific and Technical Information Branch ; [Springfield, Va.: For sale by the National Technical Information.

Turbulent boundary layer over solid and porous surfaces with small roughness. Turbulent boundary layer over porous surfaces with different surfacegeometries. 17 August Recommended. Turbulent boundary layer over porous surfaces with different surfacegeometries.

Turbulent boundary layers, especially at high Reynolds numbers, are very sensitive to wall is because any roughness element that protrudes through the viscous sublayer modifies the law of the wall.

The effect of wall roughness on the boundary layer depends on the size, shape, and spacing of the elements. Results are given for such a body with a (1) smooth, solid surface; (2) a sandpaper roughened, solid surface; (3) a sintered metal, porous surface; (4) a ""smooth'' performated titanium surface; (5) a rough, solid surface made of fine diffusion bonded screening; and (6) a rough, porous surface made of the same by: 3.

TURBULENT BOUNDARY LAYER OVER SOLID AND POROUS SURFACES WITH SMALL ROUGHNESS By Fred Y. Kong, Joseph A. Schetz, and Fayette Collier Virginia Polytechnic Institute and State University INTRODUCTION Over the years, considerable effort has been devoted to the study of turbulent boundary layer flow over porous or permeable surfaces with injection.

The first flow to address is the flat plate boundary the kL-scale is built to behave linear in the near-wall region to give a relative grid independency, it is important to check the effect of the grid refinement at the wall on the predicted friction perform tests in boundary layers, the k – kL EARSM-WJ model has been implemented in a parabolic boundary layer code.

turbulent boundary layers is being done continuously. The major aspects to researches are a) Study of turbulent boundary layer when subjected to varying pressure gradients. b) The study of fluid removed or injected from or into the flow.

c) Various obstacles are placed in the boundary layers. d) The wall roughness changes along the plate. F. Kong and J. Schetz, “ Turbulent boundary layer over solid and porous surfaces with small roughness,” in 19th Aerospace Sciences Meeting, Aerospace Sciences Meetings (American Institute of Aeronautics and Astronautics, ).

Google Scholar Crossref; G. Results from a wind tunnel study of aerodynamically rough turbulent boundary-layer flow over a sinusoidal surface are presented. The waves had a maximum slope (ak) of and two surface roughnesses were the relatively rough surface the flow separated in the wave troughs while for the relatively smooth surface it generally remained attached.

Turbulent boundary layer over solid and porous surfaces with small roughness. and Reynolds stress in the untripped boundary on a large diameter axisymmetric body. Results are given for such a body with a (1) smooth, solid surface; (2) a sandpaper roughened, solid surface; (3) a sintered metal, porous surface; (4) a ""smooth'' performated.

A new analytical expression for velocity profile in a fully developed turbulent boundary layer above a porous surface subject to flow injection is derived by solving the coupled Reynolds equations and turbulent kinetic energy equation. In this study, they extended the expression of the aerodynamic resistance term that they developed for flat surfaces, in which the piecewise boundary layer thickness under turbulent air flow over.

effects of surface roughness on a turbulent boundary layer over a two-dimensional hill under neutral conditions by using a hot wire Constant Temperature Anemometer (CTA) system with a split-fibre probe.

Rough surface conditions were modeled by placing two types of windbreak fence on the hill surface. Its porosities are 0% and 50%. Measurements. Abstract. The turbulent boundary layer over three porous walls with different surface geometries was studied in order to investigate the individual influences of porosity and small roughness, as well as their combined effects, on turbulent boundary layer behavior.

Mean Velocity Profiles - Turbulent Boundary Layers: Near a solid boundary the flow has a distinct structure, called a boundary layer. The most important aspect of a boundary layer is that the velocity of the fluid goes to zero at the boundary.

This is called the "no. [9] Schetz J. and Kong F., “ Turbulent Boundary Layer over Solid and Porous Surfaces with Small Roughness,” AIAA PaperGoogle Scholar [10] Kong F. and Schetz J., “ Turbulent Boundary Layer over Porous Surfaces with Different Surface Geometries,” AIAA PaperGoogle Scholar.

The turbulent boundary layer over three porous walls with different surface geometries was studied in order to investigate the individual influences of porosity and small roughness, as well as their combined effects, on turbulent boundary layer behavior.

Kong, F. & Schetz, J. Turbulent boundary layer over porous surfaces with different surface geometries. AIAA Paper Laadhari, F. Reynolds number effect on the dissipation function in wall-bounded flows.

The layer of air over the wing's surface that is slowed down or stopped by viscosity, is the boundary layer. There are two different types of boundary layer flow: laminar and turbulent. Laminar boundary layer flow. The laminar boundary is a very smooth flow, while the turbulent boundary layer contains swirls or "eddies.".

High-resolution, 3-D large eddy simulations are conducted to study the physics of flow past 2-D solid and porous vertical plates of height H mounted on a horizontal surface (no bottom gap) with a fully developed, turbulent incoming flow.() investigated the e ect of small scale roughness over smooth, rough, and porous surfaces on turbulent boundary layers over blu bodies.

The porous boundaries consisted of perforated sheets and mesh screens. These experiments showed that the turbulent Reynolds stresses increased near the interface, as did the skin friction. However, it is.The interactions between turbulent free flow and flow in a porous medium are of key interest in different fields, e.g., meteorology, agriculture, building physics, and aerospace engineering.

Properly understanding the strongly coupled exchange processes between the two domains is crucial to describing these interactions. In (Mosthaf et al.

in Water Resour Res 47(10):W, doi: