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R. D. Cess

Bio: R. D. Cess is an academic researcher from Westinghouse Electric. The author has contributed to research in topics: Heat transfer & Heat transfer coefficient. The author has an hindex of 10, co-authored 10 publications receiving 2590 citations.

Papers
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Book
01 Jan 1978

1,137 citations

Book
01 Jun 1978
TL;DR: In this article, the authors describe work which has been carried out under the subject grant during the period from April 1, 1961, to October 1, 2011, with technical supervision and guidance provided by Mr. Seymour Lieblein, Chief, Flow Physics Branch, NASA Lewis Research Center, Cleveland, Ohio.
Abstract: The pm-pose of this report is to describe work which has been carried out under the subject grant during the period from April 1, 1961, to October 1, 1961. Technical supervision and guidance of the work was provided by Mr. Seymour Lieblein, Chief, Flow Physics Branch, NASA Lewis Research Center, Cleveland, Ohio.

1,127 citations

Journal ArticleDOI
TL;DR: In this paper, an analytical study has been made to determine the heat transfer characteristics of a stagnation point flow in which there are temperature-dependent heat sources or sinks for a Prandtl number of 0.7.
Abstract: An analytical study has been made to determine the heat transfer characteristics of a stagnation point flow in which there are temperature-dependent heat sources or sinks. Results have been obtained for both strong and weak sources or sinks for a Prandtl number of 0.7. An analytical method, applicable to all Prandtl numbers, was utilized which circumvented the need for extensive numerical solutions and which, at the same time, provided a closed-form representation for the heat transfer. A few numerical solutions were carried out to verify the method.

70 citations

Journal ArticleDOI
TL;DR: In this article, the first eigenvalues and constants for heat transfer to laminar flow between parallel flat plates with a symmetrically prescribed wall heat flux were presented, as well as asymptotic expressions for these quantities.
Abstract: The first three eigenvalues and constants, as well as asymptotic expressions for these quantities, are presented for heat transfer to laminar flow between parallel flat plates with a symmetrically prescribed wall heat flux.

57 citations


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Journal ArticleDOI
TL;DR: In this article, the spectral energy distribution of the reflected light from an object made of a specific real material is obtained and a procedure for accurately reproducing the color associated with the spectrum is discussed.
Abstract: This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic.

1,133 citations

Proceedings ArticleDOI
01 Jan 1984
TL;DR: In this paper, a method is described which models the interaction of light between diffusely reflecting surfaces, and the resultant surface intensities are independent of observer position, and thus environments can be preprocessed for dynamic sequences.
Abstract: A method is described which models the interaction of light between diffusely reflecting surfaces. Current light reflection models used in computer graphics do not account for the object-to-object reflection between diffuse surfaces, and thus incorrectly compute the global illumination effects. The new procedure, based on methods used in thermal engineering, includes the effects of diffuse light sources of finite area, as well as the “color-bleeding” effects which are caused by the diffuse reflections. A simple environment is used to illustrate these simulated effects and is presented with photographs of a physical model. The procedure is applicable to environments composed of ideal diffuse reflectors and can account for direct illumination from a variety of light sources. The resultant surface intensities are independent of observer position, and thus environments can be preprocessed for dynamic sequences.

1,078 citations

Journal ArticleDOI
TL;DR: In this paper, a scheme to represent the impact of urban buildings on airflow in mesoscale atmospheric models is presented, where buildings are not explicitly resolved, but their effects on the grid-averaged variables are parameterised.
Abstract: A scheme to represent the impact of urban buildings on airflow in mesoscale atmospheric models is presented. In the scheme, the buildings are not explicitly resolved, but their effects on the grid-averaged variables are parameterised. An urban quarter is characterised by a horizontal building size, a street canyon width and a building density as a function of height. The module computes the impact of the horizontal (roof and canyon floor) and vertical (walls) surfaces on the wind speed, temperature and turbulent kinetic energy. The computation of the shortwave and longwave radiation, needed to compute the temperature of the urban surfaces, takes into account the shadowing and radiation trapping effects induced by the urban canyons. The computation of the turbulent length scales in the TKE equation is also modified to take into account the presence of the buildings. The parameterisation is introduced into a mesoscale model and tested in a bidimensional case of a city over flat terrain. The new parameterisation is shown to be able to reproduce the most important features observed in urban areas better than the traditional approach which is based only on the modification of the roughness length, thereby retaining the Monin-Obukhov similarity theory. The new surface exchange parameterisation is furthermore shown to have a strong impact on the dispersion characteristics of air pollutants in urban areas.

881 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of surface roughness on the three primary components of a reflectance model is analyzed in detail, and the conditions that determine the validity of the model are clearly stated.
Abstract: Reflectance models based on physical optics and geometrical optics are studied. Specifically, the authors consider the Beckmann-Spizzichino (physical optics) model and the Torrance-Sparrow (geometrical optics) model. These two models were chosen because they have been reported to fit experimental data well. Each model is described in detail, and the conditions that determine the validity of the model are clearly stated. By studying reflectance curves predicted by the two models, the authors propose a reflectance framework comprising three components: the diffuse lobe, the specular lobe, and the specular spike. The effects of surface roughness on the three primary components are analyzed in detail. >

737 citations

01 Apr 1975
TL;DR: In this article, the authors compared a variety of solar concentrators in terms of their most important general characteristics, namely concentration, acceptance angle, sensitivity to mirror errors, size of reflector area and average number of reflections.
Abstract: Even though most variations of solar concentrators have been studied or built at some time or other, an important class of concentrators has been overlooked until very recently. These novel concentrators have been called ideal because of their optical properties, and an example, the compound parabolic concentrator, is being tested at Argonne National Laboratory. Ideal concentrators differ radically from conventional instruments such as focussing parabolas. They act as radiation funnel and do not have a focus. For a given acceptance angle their concentration surpasses that of other solar concentrators by a factor of two to four, but a rather large reflector area is required. The number of reflections varies with angle of incidence, with an average value around one in most cases of interest. In order to help provide a rational basis for deciding which concentrator type is best suited for a particular application, we have compared a variety of solar concentrators in terms of their most important general characteristics, namely concentration, acceptance angle, sensitivity to mirror errors, size of reflector area and average number of reflections. The connection between concentration, acceptance angle and operating temperature of a solar collector is analysed in simple intuitive terms, leading to a straightforward recipe for designing collectors with maximal concentration (no radiation emitted by the absorber must be allowed to leave the concentrator outside its acceptance angle). We propose some new concentrators, including the use of compound parabolic concentrators as second stage concentrators for conventional parabolic or Fresnel mirrors. Such a combination approaches the performance of an ideal concentrator without demanding a large reflector; it may offer significant advantages for high temperature solar systems.

483 citations