Darrell W Pepper

Parameter estimation assumes that the model is an accurate representation of the system being studied and that any deviations are caused by measurement noise. For real experimental data this is often not the case. Clearly, the model will constructed to the highest fidelity by the analyst but when it is deficient, the remedy is not always obvious. One approach is to include a discrepancy function which one hopes will resolve any differences. The paper describes the use of such a function combined with Kalman filtering and meshless FEA.

... SUPERCOMPUTING IN HEAT TRANSFER. Darrell Pepper University of Nevada Las Vegas, Las Vegas, NV 89154; Purdue University Calumet, IN, USA. Ashley Emery Department of Mechanical Engineering, University of Washington, USA. begell house, inc. ...

... A three-dimensional, time-split chapeau function procedure is discussed by Pepper et al. [6]. ... 1-36, 1975. 13. A. J. Baker, M. 0. Soliman, and D. W. Pepper, A Time-Split Finite Element Algorithm for Environmental Release Prediction, Finite Elements in Water Re-sources, vol. ...

ABSTRACT A numerical model of the residual heat associated with stored nuclear waste casks proposed for long-term storage in Yucca Mountain has been developed. The Yucca Mountain Repository, located about 100 miles from Las Vegas, NV, is the proposed long-term geologic repository for high-level nuclear waste. STAR-CD, one of several commercial computational fluid dynamics packages being used for the assessment studies, was used to establish the numerical model. The model was developed to simulate the fluid flow and heat transfer within the drift tunnels generated by the waste casks over a 10,000-year time cycle. The model shows that the heat generated from within the casks is partially removed by ventilating air moving through the drifts and conduction through the drift walls. Thermal radiation was found to have little effect on overall cooling compared to the roles of natural convection adjacent to the casks and forced convection from the drift ventilation.

A finite element model is developed and used to simulate three-dimensional compressible fluid flow on a massively parallel computer. The algorithm is based on a Petrov-Galerkin weighting of the convective terms in the governing equations. The discretized time-dependent equations are solved explicitly using a second-order Runge-Kutta scheme. A high degree of parallelism has been achieved utilizing a MasPar MP-2 SIMD computer. An automated conversion program is used to translate the original Fortran 77 code into the Fortran 90 needed for parallelization. This conversion program and the use of compiler directives allows the maintenance of one version of the code for use on either vector or parallel machines. 17 refs.

The need to accurately calculate the transport of hazardous material is paramount to environmental safety and health activities, as well as to establish a sound emergency response capability, in the western United States and at the Nevada Test Site (NTS). Current efforts are under way at the University of Nevada, Las Vegas (UNLV) and the NOAA Air Resources Laboratory in

The primary objective of this textbook is to introduce the finite element method in a clear, concise manner using ismple examples. the author`s intent is to provide a book free of jargon and free of abstract theoretical conepts. The approahc is to teach the method through simple one-dimensional problems which can be solved manually. The procedures are then generalized to two and three dimensions.

Three adaptive FEM algorithms based on mesh refinement (h-adaptation), mesh enrichment (p-adaptation) and the combination of both (hp-adaptation) are employed to solve incompressible fluid flow problems including convective heat transfer effects. Test cases of natural convection in a square cavity with different Rayleigh numbers are solved using primitive variables in a modified finite element approach employing the three adaptive strategies. Results show excellent agreement among benchmark data available in the literature. Keywords: h-, p-, hp- adaptation, FEM, natural convection. 1 Introduction The finite element method (FEM) is a popular numerical tool used in many heat transfer and fluid flow simulations. The FEM is capable of easily dealing with irregular geometries and has the ability to implement enhanced accuracy using general-purpose algorithms. Adaptive FEM is especially attractive since it can dynamically control mesh characteristics to obtain desired accuracy. Following ...

ABSTRACT A hybrid numerical model has been developed to simulate contaminant dispersion within an aircraft interior. A two-equation Low-Reynolds-Number adaptive FEM model is used for simulating turbulent flow within an aircraft. Coupled with Lagrangian Particle Transport Technique, contaminant dispersion within aircraft interiors can be accurately simulated. Mesh independent studies can be avoided when using the adaptive technology, an L2 norm error estimator is used to guide the adaptation procedure. By using the adaptive algorithm, mesh independent studies can be avoided.

ABSTRACT The investigation of laminar natural convection in vertical channels with multiple obstructions on opposite walls is conducted using an h-adaptive FEM algorithm. The adaptive model uses an L2 norm based a posteriori error estimator with a semi-implicit, time-stepping projection technique. The advection terms are treated using an explicit Adams Bashforth method while the diffusion terms are advanced by an implicit Euler scheme. By using the adaptive algorithm, mesh independent studies can be avoided. Results are obtained for thermal and flow patterns including average Nusselt numbers for different parameters (Rayleigh number, aspect ratio and locations of obstructions).

ABSTRACT A three-step hp-adaptive finite element model (FEM) is employed to solve the governing equations for incompressible flow including mass and thermal transport. The adaptive FEM uses both mesh enrichment (h-adaptation) and spectral order incensement (p-adaptation) to maximize the rate of decrease of the interpolation error. The three-step adaptive methodology can be used to solve a wide variety of problems related to incompressible viscous flow including mass dispersion along with thermal transport. Highly accurate solutions are obtained using an optimally refined final mesh. The L2 energy norm is calculated to guide the adaptation procedure. Simulation results for incompressible flow over a backward facing step, natural convection in a partitioned enclosure and mass transport within a partitioned enclosure under thermal effects are presented. Results are compared with experimental data and numerical simulations reported in the literature. The efficiency of the proposed numerical technology is discussed.

ABSTRACT Numerical results are presented for a set of convective thermal flow problems using an hp-adaptive finite element technique. The hp-adaptive model is based on mesh refinement and spectral order incensement to produce enhanced accuracy while attempting to minimize computational requirements. An a-posteriori error estimator based on the L2 norm is employed to guide the adaptation procedure. Example test cases consisting of natural convection in a differentially heated enclosure, flow with forced convection heat transfer over a backward facing step and natural convection within an enclosed partition are presented. Numerical results are compared with published data in the literature.

ABSTRACT Calculating wind velocities accurately and efficiently is the key to successfully assessing wind fields over irregular terrain. In the finite element method, decreasing individual element size (increasing the mesh density) and increasing shape function interpolation order are known to improve accuracy. However, computational speed is typically impaired, along with tremendous increases in computational storage. This problem becomes acutely obvious when dealing with atmospheric flows. An h-adaptation scheme, which allows one to start with a coarse mesh that ultimately refines in high gradients regions, can obtain high accuracy at reduced computational time and storage. H-adaptation schemes have been shown to be very effective in compressible flows for capturing shocks [1], but have found limited use in atmospheric wind field simulations [2]. In this paper, an h-adaptive finite element model has been developed that refines and unrefines element regions based upon velocity gradients. An objective analysis technique is applied to generate a mass consistent 3-D flow field utilizing sparse meteorological data. Results obtained from the PSU/NCAR MM5 atmospheric model are used to establish the initial velocity field in lieu of available meteorological tower data. Wind field estimations for the northwest area of Nevada are currently being examined as potential locations for wind turbines.