Model Descriptions

HOTMAC

Check out the HOTMAC overview slide presentation. It contains model equations, representative applications, and a list of publications.
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Download a draft version of the HOTMAC Input Guide, LA-UR-98-1365 (1998). This guide describes the format of the input data file.
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Details on the model equations and numerical methods can be found in The Los Alamos National Laboratory Atmospheric Transport and Diffusion Models: Users Manual, Williams, Yamada, Bunker, and Niccum (1989).
Contact us for a copy.

A summary of recent research on the sensitivity of the HOTMAC-produced meteorological fields to the type of turbulence parameterization can be downloaded. This work was a collaborative effort with Arizona State Univ.
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Information on urban canopy parameterizations in HOTMAC can be found in Urban canopy parameterizations for use in mesoscale meteorological models, Brown and Williams, 2nd AMS Urban Env. Symp., Albuquerque, NM, LA-UR-98-3831 (1988).
Download 0.08 Mb pdf.

List of HOTMAC-related pubs.
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RAPTAD

RAPTAD (RAndom Particle Transport And Diffusion) is a Lagrangian random-walk/puff dispersion model used to estimate concentration distributions from point, line, and area sources. It utilizes 3-d wind, temperature, and turbulence fields to compute the transport and dispersion of pollutants in complex terrain. Stratification, wind shear, and plume rise are accounted for explicitly. Model development is ongoing in D-4.

Check out the RAPTAD overview slide presentation. It contains model equations, representative applications, and a list of publications.
Download 0.2 Mb pdf

A good overview of the HOTMAC-RAPTAD modeling system is found in A microcomputer-based forecasting model: potential applications for emergency response plans and air quality studies, Williams and Yamada, J. Air Waste Manage. Assoc., v40, pp 1266-1274 (1990).
Contact us for a copy.

View a gif movie of a HOTMAC/RAPTAD simulated plume release. The movie shows neutrally-buoyant particles being transported by the mean and turbulent wind fields for 3 days of a 30 day simulation (Sept. 10-12, 1994) in the Paso del Norte area.

Visit Yamada Science and Art and Sandia National Laboratory to learn about their HOTMAC/RAPTAD modeling efforts.

HIGRAD

HIGRAD (HIgh GRADient) is a computational fluid dynamics/meteorological model used to predict 3-d wind, temperature, moisture and turbulence fields in complex terrain and in built-up urban environments. It includes the traditional meteorological capabilities (surface energy budget, long and shortwave transmission, Coriolis force, cloud and precipitation dynamics, stratification, Monin-Obukhov similarity), but is capable of being applied at very small scales, traditionally the realm of CFD codes. The code has compressible and anelastic versions, solves for scalar variables (e.g., concentration) in the Eulerian framework, employs a Large Eddy Simulation turbulence closure, and has been massively parallelized. Model development is ongoing in EES-8 and D-4.

High fidelity urban scale modeling, HIGRAD "factsheet", LA-UR-01-1422 (2001).
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Simulations of flow around a cubical building: comparison with towing tank data and assessment of radiatively-induced thermal effects, Smith, W.S., J. Reisner, J. Kao, accepted by Atmospheric Environment, LA-UR-00-5208 (2001).
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Large-eddy and Gaussian simulations of downwind dispersion from large-building HVAC exhaust, DeCroix, Smith, Streit, and Brown, 1999, 11th Joint AMS/AWMA Conf. Appl. Air Poll. Met., Long Beach, CA, Jan. 2000, LA-UR-99-5354 (1999).
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Visit the EES-8 wild fire modeling site.

Tracer modeling in an urban environment, Reisner, Smith, Bossert, and Winterkamp, 2nd AMS Urb. Env. Conf., Albuquerque, NM, LA-UR-98-3563 (1998).
Download 1.6 Mb pdf

Application of the Newton-Krylov method to geophysical flows, Reisner, J., V. Mousseau, and D. Knoll, submitted to Mon. Wea. Rev. (2000).

Multiscale modeling of air flow in Salt Lake City and the surrounding region, Brown, M., M. Leach, R. Calhoun, W.S. Smith, D. Stevens, J. Reisner, R. Lee, N.-H. Chin, & D. DeCroix, ASCE Structures Congress 2001, Wash. DC, LA-UR-01-509 (2001).

Numerical modeling from mesoscale to urban scale to building scale, Brown, M., M. Leach, J. Reisner, D. Stevens, W.S. Smith, H.N. Chin, S. Chan, & R. Lee, 3rd AMS Urban Env. Symp., Davis, CA. LA-UR-00-2579 (2000).

GASFLOW

GASFLOW is a computational fluid dynamics model applied to solving internal and external engineering type flows. The code accounts for turbulent mixing, combustion, and chemical kinetics of gases and aerosol species, as well as heat transfer and condensation to walls and structures. It solves the compressible form of the Navier-Stokes conservation equations using the ICED-ALE numerical scheme. Model development and application is ongoing in D-4.

View the GASFLOW overview slide presentation. It contains a model description, representative applications, and a list of publications.
Download x.x Mb pdf (coming soon)

QWIC-2D

QWIC-2D is a simple diagnostic wind model that we have developed for quickly obtaining a mass-consistent wind field from wind measurements. This model will be the basis for QWIC-URB, a 3D diagnostic wind model that includes buildings.

QWIC-2D DWM v1.0 User's Guide, Pardyjak, E. and M. Brown, LA-UR-00-2578 (2000).
Download 0.2 Mb pdf 

Analytic Models

We have been involved in the development and application of analytic dispersion models, including Gaussian and non-Gaussian plume, concentration fluctuation, and street canyon dispersion modeling.

Plume descriptors derived from a non-Gaussian concentration model, Brown, Arya, and Snyder, At. Env., v 31, pp 183-189 (1997).
Contact us for a copy.

Vertical dispersion from surface and elevated releases: an investigation of a non-Gaussian plume model, Brown and Arya, Jour. Appl. Meteor., v 32, pp 491-505 (1993).
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Puff meander model: user's guide, Brown, LA-UR-99-4676 (1999).
Download 1.4 Mb pdf.

Introduction to a non-local mixing model for the prediction of the pdf of velocity fluctuations in a BL flow, Brown and Arya, AMS 11th Symp. on Boundary Layers and Turbulence, Charlotte, NC., LA-UR-94-3992 (1995).
Contact us for a copy.