QUIC-URB and QUIC-fire extension to complex terrain: Development of a terrain-following coordinate system

Journal Article · Wed Nov 16 00:00:00 EST 2022 · Environmental Modelling and Software

DOI:https://doi.org/10.1016/j.envsoft.2022.105579· OSTI ID:1900496

Robinson, David Joseph ^[1]; Brambilla, Sara ^[2]; Brown, Michael John ^[2]; Conry, Patrick Tomas ^[2]; Quaife, Bryan ^[3]; Linn, Rod Ray ^[2]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Florida State Univ., Tallahassee, FL (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
3. Florida State Univ., Tallahassee, FL (United States)

Ensemble-based approaches to prescribed fire planning cannot be supported by CFD-based models like FIRETEC and WFDS because they are too computationally expensive and cannot leverage LES approaches like CAWFE and WRF-SFIRE because too coarse of resolution. QUIC-Fire was developed to fill this gap but it cannot currently address complex terrain, typical for instance of the Western United States. In this paper, we describe the extension of the diagnostic wind model QUIC-URB, the wind engine of QUIC-Fire, to a terrain-following coordinate system. In particular, the paper presents the mathematical derivation of the wind solver leading to a linear system of equations that are solved through the successive over-relaxation method. The model is validated against a standard test used in previous works (the Askervein Hill) and against a new dataset from measurements in the Socorro Mountains, New Mexico. The terrain-following implementation captured the correct phenomenology for the isolated Askervein Hill, with a wind speed up at the top of the hill. We report the model agreed well with measurements on the upwind side of the peak, but overestimated speed-up on the downwind side of the hill. This is due to the inability of the model to generate flow separation and wake-eddy dynamics. On a common laptop, the divergence-free wind field was obtained in 6 s, making the solver appealing for coupled fire–atmosphere simulations. The Socorro Mountain was highly complex, with many cliff faces, peaks, and valleys. Although the model captures the magnitude and direction of inlet and outlet areas of the domain, it performs rather poorly in the valley region and in the regions near the steep cliffs. Hence, the model shows good agreement with data in areas of open sloped terrain but lacks in areas where flow separation and thermally driven effects may be present (neither effect was addressed in this work). Results highlight that future work should focus on the implementation of parameterizations of wake-eddies, similar to QUIC-URB’s building parameterizations, and on thermodynamic-driven flow.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1900496
• Alternate ID(s): OSTI ID: 1961291
• Report Number(s): LA-UR-22-23520
• Journal Information: Environmental Modelling and Software, Journal Name: Environmental Modelling and Software Vol. 159; ISSN 1364-8152
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Complex terrain flow
Diagnostic wind model
Earth sciences
Fast-running wind solver
Prescribed fire winds scales
Terrain-following wind solver