COMMENTS ON "A NEW LOOK AT LOW-ENERGY NUCLEAR REACTION RESEARCH" (open access)

COMMENTS ON "A NEW LOOK AT LOW-ENERGY NUCLEAR REACTION RESEARCH"

Cold fusion researchers have accumulated a large body of anomalous results over the last 20 years that they claim proves a new, mysterious nuclear reaction is active in systems they study. Krivit and Marwan give a brief and wholly positive view of this body of research. Unfortunately, cold fusion researchers routinely ignore conventional explanations of their observations, and claim much greater than real accuracy and precision for their techniques. This paper attempts to equally briefly address those aspects of the field with the intent of providing a balanced view of the field, and to establish some criteria for subsequent publications in this arena.
Date: December 30, 2009
Creator: Shanahan, K.
System: The UNT Digital Library
Attainable Burnup in a LIFE Engine Loaded with Depleted Uranium (open access)

Attainable Burnup in a LIFE Engine Loaded with Depleted Uranium

The Laser Inertial Fusion-based Energy (LIFE) system uses a laser-based fusion source for electricity production. The (D,T) reaction, beside a pure fusion system, allows the option to drive a sub-critical fission blanket in order to increase the total energy gain. In a typical fusion-fission LIFE engine the fission blanket is a spherical shell around the fusion source, preceded by a beryllium shell for neutron multiplications by means of (n,2n) reactions. The fuel is in the form of TRISO particles dispersed in carbon pebbles, cooled by flibe. The optimal design features 80 cm thick blanket, 16 cm multiplier, and 20% TRISO packing factor. A blanket loaded with depleted uranium and depleted in a single batch with continuous mixing can achieve burnup as high as {approx}85% FIMA while generating 2,000 MW of total thermal power and producing enough tritium to be used for fusion. A multi-segment blanket with a central promotion shuffling scheme enhances burnup to {approx}90% FIMA, whereas a blanket that is operated with continuous refueling achieves only 82% FIMA under the same constraints of thermal power and tritium self-sufficiency. Both, multi-segment and continuous refueling eliminate the need for a fissile breeding phase.
Date: November 30, 2009
Creator: Fratoni, M.; Kramer, K. J. & Latkowski, J. F.
System: The UNT Digital Library
Conceptual Studies of a Fuel-Flexible Low-Swirl Combustion System for the Gas Turbine in Clean Coal Power Plants (open access)

Conceptual Studies of a Fuel-Flexible Low-Swirl Combustion System for the Gas Turbine in Clean Coal Power Plants

This paper reports the results of preliminary analyses that show the feasibility of developing a fuel flexible (natural gas, syngas and high-hydrogen fuel) combustion system for IGCC gas turbines. Of particular interest is the use of Lawrence Berkeley National Laboratory's DLN low swirl combustion technology as the basis for the IGCC turbine combustor. Conceptual designs of the combustion system and the requirements for the fuel handling and delivery circuits are discussed. The analyses show the feasibility of a multi-fuel, utility-sized, LSI-based, gas turbine engine. A conceptual design of the fuel injection system shows that dual parallel fuel circuits can provide range of gas turbine operation in a configuration consistent with low pollutant emissions. Additionally, several issues and challenges associated with the development of such a system, such as flashback and auto-ignition of the high-hydrogen fuels, are outlined.
Date: November 30, 2009
Creator: Smith, K.O.; Littlejohn, David; Therkelsen, Peter; Cheng, Robert K. & Ali, S.
System: The UNT Digital Library
EFFECT OF COMBUSTOR INLET GEOMETRY ON ACOUSTIC SIGNATURE AND FLOW FIELD BEHAVIOUR OF THE LOW SWIRL INJECTOR (open access)

EFFECT OF COMBUSTOR INLET GEOMETRY ON ACOUSTIC SIGNATURE AND FLOW FIELD BEHAVIOUR OF THE LOW SWIRL INJECTOR

Low Swirl Injector (LSI) technology is a lean premixed combustion method that is being developed for fuel-flexible gas turbines. The objective of this study is to characterize the fuel effects and influences of combustor geometry on the LSI's overall acoustic signatures and flowfields. The experiments consist of 24 flames at atmospheric condition with bulk flows ranging between 10 and 18 m/s. The flames burn CH{sub 4} (at {phi} = 0.6 & 0.7) and a blend of 90% H{sub 2} - 10% CH{sub 4} by volume (at {phi} = 0.35 & 0.4). Two combustor configurations are used, consisting of a cylindrical chamber with and without a divergent quarl at the dump plane. The data consist of pressure spectral distributions at five positions within the system and 2D flowfield information measured by Particle Imaging Velocimetry (PIV). The results show that acoustic oscillations increase with U{sub 0} and {phi}. However, the levels in the 90% H{sub 2} flames are significantly higher than in the CH{sub 4} flames. For both fuels, the use of the quarl reduces the fluctuating pressures in the combustion chamber by up to a factor of 7. The PIV results suggest this to be a consequence of the quarl restricting …
Date: November 30, 2009
Creator: Therkelsen, Peter L.; Littlejohn, David; Cheng, Robert K.; Portillo, J. Enrique & Martin, Scott M.
System: The UNT Digital Library
The finite temperature QCD using 2+1 flavors of domain wall fermions at Nt = 8 (open access)

The finite temperature QCD using 2+1 flavors of domain wall fermions at Nt = 8

We study the region of the QCD phase transition using 2+1 flavors of domain wall fermions (DWF) and a 16{sup 3} x 8 lattice volume with a fifth dimension of L{sub s} = 32. The disconnected light quark chiral susceptibility, quark number susceptibility and the Polyakov loop suggest a chiral and deconfining crossover transition lying between 155 and 185 MeV for our choice of quark mass and lattice spacing. In this region the lattice scale deduced from the Sommer parameter r{sub 0} is a{sup -1} {approx} 1.3 GeV, the pion mass is {approx} 300 MeV and the kaon mass is approximately physical. The peak in the chiral susceptibility implies a pseudo critical temperature T{sub c} = 171(10)(17) MeV where the first error is associated with determining the peak location and the second with our unphysical light quark mass and non-zero lattice spacing. The effects of residual chiral symmetry breaking on the chiral condensate and disconnected chiral susceptibility are studied using several values of the valence L{sub s}.
Date: November 30, 2009
Creator: Cheng, M.; Christ, N. H.; Li, M.; Mawhinney, R. D.; Renfrew, D.; Hegde, P. et al.
System: The UNT Digital Library
IN-SITU ASSAY OF TRANSURANIC RADIONUCLIDES IN THE VADOSE ZONE USING HIGH-RESOLUTION SPECTRAL GAMMA LOGGING - A HANFORD CASE STUDY (open access)

IN-SITU ASSAY OF TRANSURANIC RADIONUCLIDES IN THE VADOSE ZONE USING HIGH-RESOLUTION SPECTRAL GAMMA LOGGING - A HANFORD CASE STUDY

High-resolution spectral gamma logging in steel-cased boreholes is used to detect and quantify transuranic radionuclides in the subsurface. Pu-239, Pu-241, Am-241, and Np-237 are identified based on characteristic decay gammas. Typical minimum detectable levels are on the order of 20 to 40 nCi/g. In intervals of high transuranic concentrations, gamma rays from other sources may complicate analysis and interpretation. Gamma rays detected in the borehole may originate from three sources: decay of the parent transuranic radionuclide or a daughter; alpha interactions; and interactions with neutrons resulting from either spontaneous fission or alpha particle interactions.
Date: November 30, 2009
Creator: VJ, ROHAY; P, HENWOOD & R, MCCAIN
System: The UNT Digital Library
Lattice super-Yang-Mills using domain wall fermions in the chiral limit (open access)

Lattice super-Yang-Mills using domain wall fermions in the chiral limit

None
Date: November 30, 2009
Creator: Giedt, J.; Brower, R.; Catterall, S.; Fleming, G. & Vranas, P.
System: The UNT Digital Library
Analysis of Voltage Signals from Superconducting Accelerator Magnets (open access)

Analysis of Voltage Signals from Superconducting Accelerator Magnets

We present two techniques used in the analysis of voltage tap data collected during recent tests of superconducting magnets developed by the Superconducting Magnet Program at Lawrence Berkeley National Laboratory. The first technique was used on a quadrupole to provide information about quench origins that could not be obtained using the time-of-flight method. The second technique illustrates the use of data from transient flux imbalances occurring during magnet ramping to diagnose changes in the current-temperature margin of a superconducting cable. In both cases, the results of this analysis contributed to make improvements on subsequent magnets.
Date: October 30, 2009
Creator: Lizarazo, J.; Caspi, S.; Ferracin, P.; Joseph, J.; Lietzke, A. F.; Sabbi, G. L. et al.
System: The UNT Digital Library
ATF2 Commissioning (open access)

ATF2 Commissioning

ATF2 is a final-focus test beam line that aims to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction has been finished at the end of 2008 and the beam commissioning of ATF2 has started in December of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.
Date: October 30, 2009
Creator: Seryi, A.; Christian, G.; Parker, B.; Schulte, D.; Delahaye, J. -P.; Tomas, R. et al.
System: The UNT Digital Library
Branching fractions and charge asymmetries in charmless hadronic decays at BABAR (open access)

Branching fractions and charge asymmetries in charmless hadronic decays at BABAR

We present measurements of branching fraction, polarization and charge asymmetry in charmless hadronic B decays with {eta}, {eta}{prime}, {omega}, and b{sub 1} in the final state. All the results use the final BABAR dataset.
Date: October 30, 2009
Creator: Biassoni, Pietro
System: The UNT Digital Library
A Concept of Plasma Wake Field Acceleration Linear Collider (PWFA-LC) (open access)

A Concept of Plasma Wake Field Acceleration Linear Collider (PWFA-LC)

Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for a shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective that the present microwave technologies. A concept of a PWFA-based Linear Collider (PWFA-LC) has been developed and is described in this paper. The drive beam generation and distribution, requirements on the plasma cells, and optimization of the interaction region parameters are described in detail. The R&D steps needed for further development of the concept are also outlined.
Date: October 30, 2009
Creator: Seryi, Andrei; Hogan, Mark; Pei, Shilun; Raubenheimer, Tor; Tenenbaum, Peter; Katsouleas, Tom et al.
System: The UNT Digital Library
Connecting Reionization to the Local Universe (open access)

Connecting Reionization to the Local Universe

We present results of combined N-body and three-dimensional reionization calculations to determine the relationship between reionization history and local environment in a volume 1 Gcp h$sup -1$ across and a resolution of about 1 Mpc. We achieve this by applying three dimensional simulations of reionization, based on the extended Press-Schechter formalism, to the same initial conditions as the N-body simulations. We resolve about 2 X 10$sup 6$ halos of mass greater than ~ 10$sup 12$M at z = 0, and determine the relationship between halo mass and reionization epoch for galaxies and clusters. For our fiducial reionization model, in which reionization begins at z ~ 15 and ends by z ~ 6, we find a strong bias for cluster-size halos to be in the regions which reionized first, at redshifts 10 < z < 15. Consequently, material in clusters was reionized within relatively small regious, on the order of a few Mpc, implying that all clusters in our calculation were reionized by their own progenitors. Milky Way mass halos were on average reionized later and by larger regions, with a distribution most similar to the global one, indicating that low mass halos are nearly uncorrelated with reionization when only halo …
Date: October 30, 2009
Creator: Alvarez, Marcelo
System: The UNT Digital Library
Constraining Emission Models of Luminous Blazar Sources (open access)

Constraining Emission Models of Luminous Blazar Sources

Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy ({gamma}-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of {gamma}-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and {gamma}-ray frequencies. We also propose that the parsec-scale blazar activity can …
Date: October 30, 2009
Creator: Sikora, Marek; Stawarz, Lukasz; Moderski, Rafal; Nalewajko, Krzysztof & Madejski, Greg
System: The UNT Digital Library
Construction and Performance of the BaBar DIRC (open access)

Construction and Performance of the BaBar DIRC

The new type of ring-imaging Cherenkov detector technology called DIRC (an acronym for Detection of Internally Reflected Cherenkov (Light)) has been used successfully for hadronic particle identification in the BABAR experiment at the B Factory (PEP-II) located at the SLAC National Accelerator Laboratory. This paper describes the R&amp;D for and the construction of the DIRC radiator bars and the performance of the DIRC during more than eight years of B Factory operation.
Date: October 30, 2009
Creator: Schwiening, Jochen
System: The UNT Digital Library
Free Electron Laser for Gamma-Gamma Collider at a Low-Energy Option of International Linear Collider (open access)

Free Electron Laser for Gamma-Gamma Collider at a Low-Energy Option of International Linear Collider

Different scenarios of a start-up with International Linear Collider (ILC) are under discussion at the moment in the framework of the Global Design Effort (GDE). One of them assumes construction of the ILC in stages from some minimum CM energy up to final target of 500 GeV CM energy. Gamma-gamma collider with CM energy of 180GeV is considered as a candidate for the first stage of the facility. In this report we present conceptual design of a free electron laser as a source of primary photons for the first stage of ILC.
Date: October 30, 2009
Creator: Saldin, Evgeny; Schneidmiller, Evgeny; Yurkov, Mikhail & Seryi, Andrei
System: The UNT Digital Library
Laser smoothing of sub-micron grooves in hydroxyl-rich fused silica (open access)

Laser smoothing of sub-micron grooves in hydroxyl-rich fused silica

Nano- to micrometer-sized surface defects on UV-grade fused silica surfaces are known to be effectively smoothed through the use of high-temperature localized CO{sub 2} laser heating, thereby enhancing optical properties. However, the details of the mass transport and the effect of hydroxyl content on the laser smoothing of defective silica at submicron length scales is still not completely understood. In this study, we examine the morphological evolution of sub-micron, dry-etched periodic surface structures on type II and type III SiO{sub 2} substrates under 10.6 {micro}m CO{sub 2} laser irradiation using atomic force microscopy (AFM). In-situ thermal imaging was used to map the transient temperature field across the heated region, allowing assessment of the T-dependent mass transport mechanisms under different laser-heating conditions. Computational fluid dynamics simulations correlated well with experimental results, and showed that for large effective capillary numbers (N{sub c} &gt; 2), surface diffusion is negligible and smoothing is dictated by capillary action, despite the relatively small spatial scales studied here. Extracted viscosity values over 1700-2000K were higher than the predicted bulk values, but were consistent with the surface depletion of OH groups, which was confirmed using confocal Raman microscopy.
Date: October 30, 2009
Creator: Shen, N; Matthews, M J; Fair, J E; Britten, J A; Nguyen, H T; Cooke, D et al.
System: The UNT Digital Library
LCLS Undulator Commissioning, Alignment, and Performance (open access)

LCLS Undulator Commissioning, Alignment, and Performance

The LCLS x-ray FEL has recently achieved its 1.5-Angstrom lasing and saturation goals upon first trial. This was achieved as a result of a thorough pre-beam checkout, both traditional and beam-based component alignment techniques, and high electron beam brightness. The x-ray FEL process demands very tight tolerances on the straightness of the electron beam trajectory (&lt;5 {micro}m) through the LCLS undulator system. Tight, but less stringent tolerances of {approx}100 {micro}m rms were met for the transverse placement of the individual undulator segments with respect to the beam axis. The tolerances for electron beam straightness can only be met through a beam-based alignment (BBA) method, which is implemented using large electron energy variations and sub-micron resolution cavity beam position monitors (BPM), with precise conventional alignment used to set the starting conditions. Precision-fiducialization of components mounted on remotely adjustable girders, and special beam-finder wires (BFW) at each girder have been used to meet these challenging alignment tolerances. Longer-term girder movement due to ground motion and temperature changes are being monitored, continuously, by a unique stretched wire and hydrostatic level Alignment Diagnostics System (ADS).
Date: October 30, 2009
Creator: Nuhn, Heinz-Dieter
System: The UNT Digital Library
Measurement of Branching Fractions of B decays to K1(1270)pi and K1(1400)pi and Determination of the CKM angle alpha from B0 --> a1(1260) /- pi-/ (open access)

Measurement of Branching Fractions of B decays to K1(1270)pi and K1(1400)pi and Determination of the CKM angle alpha from B0 --> a1(1260) /- pi-/

We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K{sub 1}(1270) or K{sub 1}(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation. We measure the branching fractions {Beta}(B{sup 0} {yields} K{sub 1}(1270){sup +}{pi}{sup -} + K{sub 1}(1400){sup +}{pi}{sup -}) = 3.1{sub 0.7}{sup +0.8} x 10{sup -5} and {Beta}(B{sup +} {yields} K{sub 1}(1270){sup 0}{pi}{sup +} + K{sub 1}(1400){sup 0}{pi}{sup +}) = 2.9{sub -1.7}{sup +2.9} x 10{sup -5} (&lt; 8.2 x 10{sup -5} at 90% confidence level), where the errors are statistical and systematic combined. The B{sup 0} decay mode is observed with a significance of 7.5{sigma}, while a significance of 3.2{sigma} is obtained for the B{sup +} decay mode. Based on these results, we estimate the weak phase {alpha} = (79 {+-} 7 {+-} 11){sup o} from the time dependent CP asymmetries in B{sup 0} {yields} a{sub 1}(1260){sup {+-}}{pi}{sup {-+}} decays.
Date: October 30, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Measurements of the tau Mass and Mass Difference of the tau^+ and tau^- at BABAR (open access)

Measurements of the tau Mass and Mass Difference of the tau^+ and tau^- at BABAR

The authors present the result of a precision measurement of the mass of the {tau} lepton, M{sub {tau}}, based on 423 fb{sup -1} of data recorded at the {Upsilon}(4S) resonance with the BABAR detector. Using a pseudomass endpoint method, they determine the mass to be 1776.68 {+-} 0.12(stat) {+-} 0.41(syst) MeV. They also measure the mass difference between the {tau}{sup +} and {tau}{sup -}, and obtain (M{sub {tau}{sup +}} - M{sub {tau}{sup -}})/M{sub AVG}{sup {tau}} = (-3.4 {+-} 1.3(stat) {+-} 0.3(syst)) x 10{sup -4}, where M{sub AVG}{sup {tau}} is the average value of M{sub {tau}{sup +}} and M{sub {tau}{sup -}}.
Date: October 30, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Power Saving Optimization for Linear Collider Interaction Region Parameters (open access)

Power Saving Optimization for Linear Collider Interaction Region Parameters

Optimization of Interaction Region parameters of a TeV energy scale linear collider has to take into account constraints defined by phenomena such as beam-beam focusing forces, beamstrahlung radiation, and hour-glass effect. With those constraints, achieving a desired luminosity of about 2E34 would require use of e{sup +}e{sup -} beams with about 10 MW average power. Application of the 'travelling focus' regime may allow the required beam power to be reduced by at least a factor of two, helping reduce the cost of the collider, while keeping the beamstrahlung energy loss reasonably low. The technique is illustrated for the 500 GeV CM parameters of the International Linear Collider. This technique may also in principle allow recycling the e{sup +}e{sup -} beams and/or recuperation of their energy.
Date: October 30, 2009
Creator: Seryi, Andrei
System: The UNT Digital Library
Simulations of Jitter Coupling due to Wakefields in the FACET Linac (open access)

Simulations of Jitter Coupling due to Wakefields in the FACET Linac

Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e{sup +} and e{sup -} beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed an RF-cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes. Lucretia is a Matlab toolbox for the simulation of electron beam transport systems, capable of multi-bunch tracking and wakefield calculations. With the exception of the lack of support for tracking of electrons and positrons within a single bunch train, it was well suited to the jitter coupling studies. This paper describes the jitter studies, including modifications made to Lucretia to correctly simulate tracking of mixed-species bunch trains through a lattice of magnetic elements and EM wakes.
Date: October 30, 2009
Creator: Molloy, Stephen
System: The UNT Digital Library
Stable grid refinement and singular source discretization for seismic wave simulations (open access)

Stable grid refinement and singular source discretization for seismic wave simulations

An energy conserving discretization of the elastic wave equation in second order formulation is developed for a composite grid, consisting of a set of structured rectangular component grids with hanging nodes on the grid refinement interface. Previously developed summation-by-parts properties are generalized to devise a stable second order accurate coupling of the solution across mesh refinement interfaces. The discretization of singular source terms of point force and point moment tensor type are also studied. Based on enforcing discrete moment conditions that mimic properties of the Dirac distribution and its gradient, previous single grid formulas are generalized to work in the vicinity of grid refinement interfaces. These source discretization formulas are shown to give second order accuracy in the solution, with the error being essentially independent of the distance between the source and the grid refinement boundary. Several numerical examples are given to illustrate the properties of the proposed method.
Date: October 30, 2009
Creator: Petersson, N A & Sjogreen, B
System: The UNT Digital Library
A Vernier Regulator for ILC Marx Droop Compensation (open access)

A Vernier Regulator for ILC Marx Droop Compensation

A two-part compensation scheme, Vernier Regulation, has been applied to offset the voltage droop (40% without correction) in a Marx-topology klystron modulator developed for the International Linear Collider (ILC). Coarse regulation, {+-}5%, is achieved by turning on additional Main Marx cells (Delayed Cells) sequentially as the droop reaches the cell voltage (11 kV). Further regulation to {+-}0.5% is achieved by adding a small Marx in series with the Main Marx. This Vernier Marx is composed of sixteen, 1.2 kV cells that are assembled as a seventeenth cell in the Main Marx. These Vernier Cells are turned on sequentially to generate a series of discrete corrections to the droop in the Main Marx cells with a step size {le}1% of the output voltage. As the required correction reaches 11 kV, all Vernier Cells are turned off synchronously with the turn on of a Delayed Cell. There are up to five Delayed Cells and six Vernier Marx cycles during each ILC Marx output pulse. The Vernier Marx has a local control system that will detect and respond to over-voltage and over-current errors. In this paper, a detailed description of the design, implementation and testing of the Vernier Marx is presented.
Date: October 30, 2009
Creator: Tang, Tao
System: The UNT Digital Library
Accurate Wind Characterization in Complex Terrain Using the Immersed Boundary Method (open access)

Accurate Wind Characterization in Complex Terrain Using the Immersed Boundary Method

This paper describes an immersed boundary method (IBM) that facilitates the explicit resolution of complex terrain within the Weather Research and Forecasting (WRF) model. Two different interpolation methods, trilinear and inverse distance weighting, are used at the core of the IBM algorithm. Functional aspects of the algorithm's implementation and the accuracy of results are considered. Simulations of flow over a three-dimensional hill with shallow terrain slopes are preformed with both WRF's native terrain-following coordinate and with both IB methods. Comparisons of flow fields from the three simulations show excellent agreement, indicating that both IB methods produce accurate results. However, when ease of implementation is considered, inverse distance weighting is superior. Furthermore, inverse distance weighting is shown to be more adept at handling highly complex urban terrain, where the trilinear interpolation algorithm breaks down. This capability is demonstrated by using the inverse distance weighting core of the IBM to model atmospheric flow in downtown Oklahoma City.
Date: September 30, 2009
Creator: Lundquist, K A; Chow, F K; Lundquist, J K & Kosovic, B
System: The UNT Digital Library