Ivan Catton
University of California, Los Angeles
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Featured researches published by Ivan Catton.
Nuclear Engineering and Design | 1990
B.E. Boyack; Ivan Catton; R.B. Duffey; Peter Griffith; K.R. Katsma; G.S. Lellouche; S. Levy; U.S. Rohatgi; G.E. Wilson; Wolfgang Wulff; Novak Zuber
Abstract In August 1988, the Nuclear Regulatory Commission (NRC) approved the final version of a revised rule on the acceptance of ECCS entitled “Emergency Core Cooling System; Revision to Acceptance Criteria.” The revised rule states an alternate ECCS performance analysis, based on best-estimate methods, may be used to provide more realistic estimates of plant safety margins, provided the licensee quantifies the uncertainty of the estimates and includes that uncertainty when comparing the calculated results with prescribed acceptance limits. To support the revised ECCS rule, the NRC and its contractors and consultants have developed and demonstrated a method called the Code Scaling, Applicability, and Uncertainty (CSAU) evaluation methodology. The CSAU methodology and an example application, described in this set of six papers, demonstrate that uncertainties in complex phenomena can be quantified. The methodology is structured, traceable, and practical, as is needed in the regulatory arena. It addresses in a comprehensive and systematic manner questions concerned with: (1) code capability to scale-up processes from test facility to full-scale nuclear power plant (NPP). (2) code applicability to safety studies of postulated accident scenario in a specified NPP, and (3) quantifying uncertainties of calculated results. The methodology combines a “top-down” approach to define the dominant phenomena with a “bottom-up” approach to quantify uncertainty. The methedology is able to address both: (1) uncertainties for which bias and distribution are quantifiable, and (2) uncertainties for which only a bounding value is quantifiable. The methodology is general, and therefore applicable to a variety of scenarios, plants, and codes. This paper provides an overview of the CSAU evaluation methodology and its application to a postulated cold-leg, large-break loss-of-coolant accident in a Westinghouse four-loop pressurized water reactor with 17 x 17 fuel. The code selected for this demonstration of the CSAU methodology was TRAC-PF1/MOD1, Version 14.3.
International Journal of Heat and Mass Transfer | 1972
Ivan Catton
Abstract The initiation of natural convection in a fluid confined above and below by rigid perfectly conducting surfaces and laterally by rigid perfectly insulating vertical walls that form a rectangular shape is examined. The linearized perturbation equations are obtained and by appropriate non-dimen-sionalization, they are reduced to an eigenvalue problem. The Rayleigh number is the eigenvalue and is a function of two aspect ratios (width/height and depth/height). The problem associated with satisfying the no-slip boundary conditions on all surfaces is surmounted by using the Galerkin method. Results are obtained for aspect ratios ranging from 1 8 to 12. The results are compared with experiment and found to be in good agreement.
International Journal of Heat and Mass Transfer | 1974
Ivan Catton; Portonovo S. Ayyaswamy; R.M. Clever
Solutions to the stationary two-dimensional equations of motion governing natural convection flow of a large Prandtl number Boussinesq fluid contained in a differentially heated inclined rectangular slot have been obtained by the Galerkin method. The problem has been solved for perfectly conductive and adiabatic boundary conditions on the border strips. The range of parameters investigated include: Rayleigh numbers up to 2 × 106, aspect ratios from 0.1 to 20, and tilt angles from −30° (bottom plate hotter) to + 75° (top plate hotter). These parameters describe both the conduction and boundary layer regimes. The computed flow distributions, including the appearance of multicellular flows, the temperature profiles, and the heat transfer predictions compare favorably with experimental results, and with other numerical studies.
International Journal of Heat and Mass Transfer | 2003
Andrej Horvat; Ivan Catton
Abstract A fast running computational algorithm based on the volume averaging technique (VAT) is developed to simulate conjugate heat transfer process in an electronic device heat sink. The goal is to improve computational capability in the area of heat exchangers and to help eliminate some of empiricism that leads to overly constrained designs with resulting economic penalties. VAT is tested and applied to the transport equations of airflow through an aluminum (Al) chip heat sink. The equations are discretized using the finite volume method (FVM). Such computational algorithm is fast running, but still able to present a detailed picture of temperature fields in the airflow as well as in the solid structure of the heat sink. The calculated whole-section drag coefficient, Nusselt number and thermal effectiveness are compared with experimental data to verify the computational model and validate numerical code. The comparison also shows a good agreement between FVM results and experimental data. The constructed computational algorithm enables prediction of cooling capabilities for the selected geometry. It also offers possibilities for geometry improvements and optimization, to achieve higher thermal effectiveness.
Journal of Fluid Mechanics | 1988
Jeffrey Jacobs; Ivan Catton
Three-dimensional weakly nonlinear Rayleigh-Taylor instability is analysed. The stability of a confined inviscid liquid and an overlying gas with density much less than that of the liquid is considered. An asymptotic solution for containers of arbitrary cross-sectional geometry, valid up to order e 3 (where e is the root-mean-squared initial surface slope) is obtained. The solution is evaluated for the rectangular and circular geometries and for various initial modes (square, hexagonal, axisymmetric, etc.). It is found that the hexagonal and axisymmetric instabilities grow faster than any other shapes in their respective geometries. In addition it is found that, sufficiently below the cutoff wavenumber, instabilities that are equally proportioned in the lateral directions grow faster than those with longer, thinner shape. However, near the cutoff wavenumber this trend reverses with instabilities having zero aspect ratio growing faster than those with aspect ratio near 1.
Numerical Heat Transfer Part A-applications | 2011
Feng Zhou; Ivan Catton
A numerical investigation of the thermal and hydraulic performance of 20 different plate-pin fin heat sinks with various shapes of pin cross-sections (square, circular, elliptic, NACA profile, and dropform) and different ratios of pin widths to plate fin spacing (0.3, 0.4, 0.5, and 0.6) was performed. Finite volume method-based CFD software, Ansys CFX, was used as the 3-D Reynolds-averaged Navier-Stokes Solver. A k-ω based shear-stress-transport model was used to predict the turbulent flow and heat transfer through the heat sink channels. The present study provides original information about the performance of this new type of compound heat sink.
Journal of Heat Transfer-transactions of The Asme | 1986
John G. Georgiadis; Ivan Catton
A numerical study of buoyance-driven two-dimensional convection in a fluid-saturated horizontal porous layer is reported emphasizing the nonlinear inerital effect on heat transport. The Forchheimer-Brinkman-Darcy-Boussinesq formulation and a single energy equation for the volume-average temperature are used. Closure to the wavenumber selection problem is sought through a criterion based on the Glansdorff and Prigogine theory of nonequilibrium thermodynamics. Good agreement with laboratory data and the analogy with th Rayleigh-Benard problem are corroborative facts which justify smililar non-Darcian formulations and demonstrate the role of the quadratic inertial terms in decreasing the mean convective heat transfer across the layer.
Applied Thermal Engineering | 2001
Jinliang Wang; Ivan Catton
Abstract Evaporation heat transfer in a triangular groove is enhanced by a thin fine porous layer on the groove surface. This not only improves the capillary force but also extends the evaporating surface with high heat transfer performance. The enhancement mechanism is explained and an analytical model is developed to predict evaporation heat transfer performance in a triangular groove formed by trapezoidal fins covered by a thin fine porous layer. The total heat transfer coefficient decreases with increasing liquid meniscus radii, increases with increasing of the half groove angle and the half width of the fin top surface. With receding of the liquid meniscus in the groove covered by a thin porous layer, the evaporation heat transfer performance is improved significantly. A comparison between evaporation heat transfer in triangular grooves with and without a thin porous layer, at the same conditions, shows the former is much better than the latter although the latter has a small area with a heat transfer coefficient as high as 10 8 W m −2 K −1 . In the calculation range, evaporation heat transfer in the groove covered by a thin porous layer is three to six times higher than that in the groove without a porous layer.
Journal of Heat Transfer-transactions of The Asme | 2008
Tadej Semenic; Ying-Yu Lin; Ivan Catton
Thirty biporous slugs with 3 different cluster diameters and 5 different particle diameters (15 combinations with 2 repetitions) and 12 monoporous slugs with 6 different particle diameters were sintered from spherical copper powder, and thermophysical properties were measured. The neck size ratio for all the particles was approximately 0.4. The porosity of monoporous samples was found to be independent of particle diameter and was equal to 0.28, and the porosity of biporous samples was found to be independent of cluster and particle diameters, and was equal to 0.64. The liquid permeability and maximum capillary pressure of small pores were found to be a linear function of the particle diameter. Similarly, vapor permeability was found to be a linear function of the cluster diameter The thermal conductivity of monoporous samples was measured to be 142 ±3 WImK at 42±2°C, and it was independent of particle diameter The thermal conductivity of biporous samples was found to be a function of cluster to particle diameter ratio.
Journal of Heat Transfer-transactions of The Asme | 1988
A. Mirzamoghadam; Ivan Catton
Transport phenomena associated with the heating of a stationary fluid near saturation by an inclined, partially submerged copper plate were studied analytically. Under steady-state evaporation, the meniscus profile was derived using an appropriate liquid film velocity and temperature distribution in an integral approach similar to boundary layer analysis. Derivation of the meniscus profile led to predicting heat transfer and performance as a function of angle of inclination of the plate.