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Existing view factor program, RAVFAC, was modified to accept NASTRAN and/or RAVFAC surface descriptions. Output formatting was altered to produce view factor matrices which could be directly input to NASTRAN.
The purpose of program VIEW is to compute view factors between specified surfaces and to be compatible with level 15.5 of the NASTRAN structural analysis program. Program VIEW is a modification of a (finite element) view factor computation program called RAVFAC. VIEW is designed to run on an IBM System/360 operating under OS (operating system), with a minimum region size of 110 K bytes. The actual computation of view factors is still performed exactly as it was in the original version of RAVFAC. In developing VIEW, RAVFAC was modified to satisfy the following compatibility requirements: (1) accept finite element input which can also be used as input to NASTRAN, (2) produce output (view factors) in a format which can be used as input to NASTRAN, and (3) follow NASTRAN program design so that in the future VIEW can be incorporated into NASTRAN as a subroutine. The VIEW program permits computation of the view factors between surfaces, taking into account the presence of any intermediate surfaces. VIEW also computes these view factors either by contour integration or by finite difference (double summation) methods.
Geometrical view factor of fin-tube radiators for space power plants, using fin to space ratio
VIEW is interactive program determining view factors, graphically displays surfaces, and evaluates solar irradiation of assemblage of surfaces. VIEW programs available in two machine versions. IBM PC version (LAR-14217) written in FORTRAN 77, C language, and assembly language. DEC VAX VMS version (LAR-14468) written in FORTRAN 77.
The view factors which are used in diffuse-gray radiation enclosure calculations are often computed by approximate numerical integrations. These approximately calculated view factors will usually not satisfy the important physical constraints of reciprocity and closure. In this paper several view-factor rectification algorithms are reviewed and a rectification algorithm based on a least-squares numerical filtering scheme is proposed with both weighted and unweighted classes. A Monte-Carlo investigation is undertaken to study the propagation of view-factor and surface-area uncertainties into the heat transfer results of the diffuse-gray enclosure calculations. It is found that the weighted least-squares algorithm is vastly superior to the other rectification schemes for the reduction of the heat-flux sensitivities to view-factor uncertainties. In a sample problem, which has proven to be very sensitive to uncertainties in view factor, the heat transfer calculations with weighted least-squares rectified view factors are very good with an original view-factor matrix computed to only one-digit accuracy. All of the algorithms had roughly equivalent effects on the reduction in sensitivity to area uncertainty in this case study.
VIEW is six computer programs for determining view factors, graphically displaying surfaces, and evaluating solar irradiation of assemblage of surfaces. Programs offer thermal engineer powerful system for view-factor determination. Central program of system (VIEWC) computes longwave radiantenergy exchange factors between surfaces that make up enclosure. Other VIEW programs support user working with VIEWC.
Radiation calculations begin with a determination of view (or shape) factors describing the geometrical configuration of the exchanging surfaces. These viewfactor calculations can be very involved, time consuming and expensive. This paper describes the development of an algorithm for situations in which the view between two surfaces is obscured by one or more intervening surfaces. A technique based upon the combination of the Contour Integration and Double Area Integration methods and the acceleration techniques necessary for its efficient use are described. Numerical examples are given to demonstrate the use of the technique and to describe some of the problems inherent in treating radiation in enclosures.
A numerical procedure was developed to determine geometric view factors between connected infinite strips occluded by any number of infinite circular cylinders. The procedure requires a two-dimensional cross-sectional model of the configuration of interest. The two-dimensional model consists of a convex polygon enclosing any number of circles. Each side of the polygon represents one strip, and each circle represents a circular cylinder. A description and listing of a computer program based on this procedure are included in this report. The program calculates geometric view factors between individual strips and between individual strips and the collection of occluding cylinders.
Radiation view factors for toroid calculated by digital computer
The Python code takes EnergyPlus input files and creates input for the View3D program, executes the View3D program, then inserts the respective view factors into the EnergyPlus input file, thus streamlining the process of view factor calculation and modification of the EnergyPlus input file.
View factor in radiant heat transfer calculations
Computer program, RAVFAC, calculates diffuse radiation view factors, using contour integrals. Technique is combined with finite difference /double summation/ technique to compose total program package.
The NASTRAN thermal analyzer will include the capability to perform complete thermal analyses on structures. One of the inputs to NASTRAN required to simulate radiative heat transfer between surfaces will be the view factors (also called shape factors, form factors, configuration factors) between those surfaces. The purpose of the VIEW program is to compute these view factors and produce appropriate RADMTX and RADLST output to be used as NASTRAN bulk data.
The use of Lidar (Light Detection and Ranging), an active light-emitting instrument, is becoming increasingly common for a range of potential applications. Its ability to provide fine resolution spatial and vertical resolution elevation data makes it ideal for a wide range of studies. This paper demonstrates the capability of Lidar data to measure sky view factors (SVF). The Lidar data is used to generate a spatial map of SVFs which are then compared against photographically-derived SVF at selected point locations. At each location three near-surface elevations measurements were taken and compared with collocated Lidar-derived estimated. It was found that there was generally good agreement between the two methodologies, although with decreasing SVF the Lidar-derived technique tended to overestimate the SVF: this can be attributed in part to the spatial resolution of the Lidar sampling. Nevertheless, airborne Lidar systems can map sky view factors over a large area easily, improving the utility of such data in atmospheric and meteorological models.
Simplified expressions (in comparison to currently used expressions, such as one developed by Howell, 1982) are developed for computing the view factors for rectangular perpendicular and parallel plates in the analysis of radiant exchanges between surfaces separated by a radiatively transparent medium. It is shown that the reported expressions for rectangular perpendicular and parallel plates with varying position and size having parallel boundaries satisfy the properties of the view factors.
Computer programs find the direct view factor from one surface segment to another using the Monte carlo technique, and the radioactive-transfer coefficients between surface segments. An advantage of the programs is the great generality of problems treatable and rapidity of solution from problem conception to receipt of results.
The development of a pair of computer programs to calculate the radiation exchange view factors is described. The surface generation program is based upon current graphics capabilities and includes special provisions which are unique to the radiation problem. The calculational program uses a combination of contour and double area integration to permit consideration of radiation with obstruction surfaces. Examples of the surface generation and the calculation are given.
Eckert shadow technique for radiation view factors applied to toroid inside shadow hemisphere