scholarly journals Numerical simulation of tsunami generation by cold volcanic mass flows at Augustine Volcano, Alaska

2006 ◽  
Vol 6 (5) ◽  
pp. 671-685 ◽  
Author(s):  
C. F. Waythomas ◽  
P. Watts ◽  
J. S. Walder
Keyword(s):  
Numerical Simulation ◽  
North Pacific Ocean ◽  
Debris Avalanche ◽  
Pyroclastic Flows ◽  
Tsunami Generation ◽  
Cook Inlet ◽  
Kenai Peninsula ◽  
Debris Avalanches ◽  
Short Period ◽  
Mass Flows

Abstract. Many of the world's active volcanoes are situated on or near coastlines. During eruptions, diverse geophysical mass flows, including pyroclastic flows, debris avalanches, and lahars, can deliver large volumes of unconsolidated debris to the ocean in a short period of time and thereby generate tsunamis. Deposits of both hot and cold volcanic mass flows produced by eruptions of Aleutian arc volcanoes are exposed at many locations along the coastlines of the Bering Sea, North Pacific Ocean, and Cook Inlet, indicating that the flows entered the sea and in some cases may have initiated tsunamis. We evaluate the process of tsunami generation by cold granular subaerial volcanic mass flows using examples from Augustine Volcano in southern Cook Inlet. Augustine Volcano is the most historically active volcano in the Cook Inlet region, and future eruptions, should they lead to debris-avalanche formation and tsunami generation, could be hazardous to some coastal areas. Geological investigations at Augustine Volcano suggest that as many as 12–14 debris avalanches have reached the sea in the last 2000 years, and a debris avalanche emplaced during an A.D. 1883 eruption may have initiated a tsunami that was observed about 80 km east of the volcano at the village of English Bay (Nanwalek) on the coast of the southern Kenai Peninsula. Numerical simulation of mass-flow motion, tsunami generation, propagation, and inundation for Augustine Volcano indicate only modest wave generation by volcanic mass flows and localized wave effects. However, for east-directed mass flows entering Cook Inlet, tsunamis are capable of reaching the more populated coastlines of the southwestern Kenai Peninsula, where maximum water amplitudes of several meters are possible.

A Numerical Investigation on the Volute/Diffuser Interaction due to the Axial Distortion at Impeller Exit

2000 ◽  
Author(s):  
Fahua Gu ◽  
Abraham Engeda ◽  
Mike Cave ◽  
Jean-Luc Di Liberti
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Investigation ◽  
Steady Flow ◽  
Centrifugal Compressor ◽  
Vortex Structure ◽  
Flow Model ◽  
Single Stage ◽  
Mass Flows

Abstract A numerical simulation is performed on a single stage centrifugal compressor using the commercially available CFD software, CFX-TASCflow. The steady flow is obtained by circumferentially averaging the exit fluxes of the impeller. Three runs are made at design condition and off-design conditions. The predicted performance is in agreement with experimental data. The flow details inside the stationary components are investigated, resulting in a flow model describing the volute/diffuser interaction at design and off-design conditions. The recirculation and twin vortex structure are found to explain the volute loss increase at lower and higher mass flows, respectively.

Soil history and debris avalanche deposits along the Illawarra scarpland

Soil Research ◽  
1963 ◽  
Vol 1 (2) ◽  
pp. 223 ◽  
Author(s):  
PH Walker
Keyword(s):  
Debris Avalanche ◽  
Climatic Conditions ◽  
Phase Instability ◽  
Alternate Form ◽  
The Past ◽  
Weathered Zone ◽  
Debris Avalanches ◽  
History Of

Two major periods of avalanching have occurred along the Illawarra scarpland. The older, the Scarborough formation, is characterized by a very thick, acid, weathered zone, similar to the lower mottled horizons of laterite profiles. The younger, Keira formation, has relatively shallow red and yellow earth profiles developed in it. Although its profile of deep weathering has some features in common with laterite, the Scarborough formation is not part of the general laterite surface, but represents a separate period of prolonged stability and weathering. The debris-avalanches are thought to have been deposited during excessively wet climatic conditions in the past, and they represent an alternate form of instability compared with the dry phase instability proposed for the K-cycle history of milder hillslope terrain near Nowra.

Numerical simulation of the turbulent Rayleigh–Bénard problem using subgrid modelling

1985 ◽  
Vol 158 ◽  
pp. 245-268 ◽  
Author(s):  
Thomas M. Eidson
Keyword(s):  
Numerical Simulation ◽  
Small Scale ◽  
Direct Simulation ◽  
Turbulent Natural Convection ◽  
Eddy Simulation ◽  
Subgrid Model ◽  
Short Period ◽  
Bénard Problem ◽  
Benard Problem ◽  
Rayleigh Benard

A numerical simulation of turbulent natural convection (the Rayleigh–Bénard problem) has been conducted using large-eddy-simulation (LES) methods and the results compared with several experiments. The development of the LES equation is outlined and discussed. The modelling of the small-scale turbulent motion (called subgrid modelling) is also discussed. The resulting LES equations are solved and data collected over a short period of time in a similar manner to the direct simulation of the governing conservation equations. An explicit, second-order accurate, finite-difference scheme is used to solve the equations. Various average properties of the resulting flow field are calculated from the data and compared with experimental data in the literature. The use of a subgrid model allows a higher value of Ra to be simulated than was previously possible with a direct simulation. The highest Ra successfully simulated was 2.5 × 106. The problems at higher values of Ra are discussed and suggestions for improvements made.

scholarly journals Effects of pore pressure in pyroclastic flows: Numerical simulation and experimental validation

2017 ◽  
Vol 44 (5) ◽  
pp. 2194-2202 ◽  
Author(s):  
V. Gueugneau ◽  
K. Kelfoun ◽  
O. Roche ◽  
L. Chupin
Keyword(s):  
Numerical Simulation ◽  
Pore Pressure ◽  
Experimental Validation ◽  
Pyroclastic Flows

scholarly journals Characteristics of debris avalanche deposits inferred from source volume estimate and hummock morphology around Mt. Erciyes, central Turkey

2018 ◽  
Vol 18 (2) ◽  
pp. 429-444 ◽  
Author(s):  
Yuichi S. Hayakawa ◽  
Hidetsugu Yoshida ◽  
Hiroyuki Obanawa ◽  
Ryutaro Naruhashi ◽  
Koji Okumura ◽  
...  
Keyword(s):  
Cross Sections ◽  
Land Surface ◽  
Flow Direction ◽  
Debris Avalanche ◽  
Caldera Wall ◽  
High Definition ◽  
Sector Collapse ◽  
Volume Estimate ◽  
Debris Avalanches ◽  
Central Turkey

Abstract. Debris avalanches caused by volcano sector collapse often form characteristic depositional landforms such as hummocks. Sedimentological and geomorphological analyses of debris avalanche deposits (DADs) are crucial to clarify the size, mechanisms, and emplacement of debris avalanches. We describe the morphology of hummocks on the northeastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion and multi-view stereo (SfM–MVS) photogrammetry, we obtained high-definition digital elevation model (DEM) and orthorectified images of the hummocks to investigate their geometric features. We estimated the source volume of the DAD by reconstructing the topography of the volcano edifice using a satellite-based DEM. We examined the topographic cross sections based on the slopes around the scar regarded as remnant topography. Spatial distribution of hummocks is anomalously concentrated at a certain distance from the source, unlike those that follow the distance–size relationship. The high-definition land surface data by RPAS and SfM revealed that many of the hummocks are aligned toward the flow direction of the debris avalanche, suggesting that the extensional regime of the debris avalanche was dominant. However, some displaced hummocks were also found, indicating that the compressional regime of the flow contributed to the formation of hummocks. These indicate that the flow and emplacement of the avalanche were constrained by the topography. The existing caldera wall forced the initial eastward flow to move northward, and the north-side caldera wall forced the flow into the narrow and steepened outlet valley where the sliding debris underwent a compressional regime, and out into the unconfined terrain where the debris was most likely emplaced on an extensional regime. Also, the estimated volume of 12–15 × 108 m3 gives a mean thickness of 60–75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche must have flowed further downstream and beyond the current DAD extent. Assessments of the DAD incorporating the topographic constraints can provide further insights into the risk and mitigation of potential disasters in the study area.

scholarly journals Development of a simplified methodology for furnace aerodynamics with vortex combustion of organic fuel modeling

2021 ◽  
Vol 2088 (1) ◽  
pp. 012016
Author(s):  
V B Prokhorov ◽  
N E Fomenko ◽  
M V Fomenko
Keyword(s):  
Numerical Simulation ◽  
Combustion Process ◽  
Organic Fuel ◽  
Direct Flow ◽  
Boiler Furnace ◽  
Short Period ◽  
Combustion Processes ◽  
Vortex Combustion ◽  
Furnace Volume ◽  
Furnace Aerodynamics

Abstract This paper describes the process of developing a simplified methodology for furnace aerodynamics during the development or modernization of combustion schemes with direct-flow burners. This technique is based on the use of numerical modeling of air movement and turbulence phenomena in the furnace volume and allows for a relatively short period of time to analyze a large number of options for the burners and nozzles location. This is its advantage in comparison with the use of experimental modeling or numerical simulation with combustion when analyzing a variety of schemes. The model was developed on the basis of validated results of combustion processes numerical simulation in the K-50 boiler furnace. The paper presents the results of calculations performed for several variants of the simplified methodology. For further use, the option that best corresponds to full-scale studies taking into account the fuel combustion process has been selected. The main states of the methodology are formulated.

scholarly journals CFD STUDY THE IMPACT OF KEY PARAMETERS ON THE DISTRIBUTION OF SMOKE AND HAZARDS IN THE PREMISES

2012 ◽  
Vol 15 (1) ◽  
pp. 27-35
Author(s):  
A. Terziev ◽  
I. Antonov ◽  
Nam Thanh Nguyen ◽  
Lien Duc Hoang
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Fire Protection ◽  
Temperature Field Distribution ◽  
Major Task ◽  
Acoustic Insulation ◽  
Short Period ◽  
Protection Systems ◽  
The Impact ◽  
Made In

In modern buildings more diverse and new polymeric combustible materials widely used as coverings, beddings, thermal and acoustic insulation, equipment and furniture are applied. Some of these elements are able to release large amounts of smoke and heat in a very short period of time. The building can get extremely dangerous situations in presence of fire. Since the major task of fire protection technique is protecting people from injury, some answers to the following questions are seeks: how smoke will be spread into the room, is there a chance to be taken away without burning spread, which are the general parameters defining distribution of smoke and hazards in the premises and etc. The solution of the problems raised above resorting to mathematical modeling of fires. For this purpose a numerical simulation of such processes are accomplished. Here are presented the results of spreading of smoke and hazards in a room occupied by people as particular attention is paid to a velocity and temperature field distribution. Based on the results of the numerical simulation, a scientific-based prognosis of the hazardous factors was made in order to optimize the work of the fire protection systems (smoke extraction systems, mechanical ventilation) by considering the physical characteristics of the room.

scholarly journals Modelling erosion and deposition in geophysical granular mass flows

2021 ◽  
Vol 52 (1) ◽  
pp. 29-32
Author(s):  
Sylvain Viroulet ◽  
Chris Johnson ◽  
Nico Gray
Keyword(s):  
Debris Flows ◽  
Large Scale ◽  
Laboratory Experiments ◽  
Pyroclastic Flows ◽  
Small Scale ◽  
Snow Avalanches ◽  
Erosion And Deposition ◽  
Granular Rheology ◽  
Scale Models ◽  
Mass Flows

During hazardous geophysical mass flows, such as rock or snow avalanches, debris flows and volcanic pyroclastic flows, a continuous exchange of material can occur between the slide and the bed. The net balance between erosion and deposition of particles can drastically influence the behaviour of these flows. Recent advances in describing the non-monotonic effective basal friction and the internal granular rheology in depth averaged theories have enabled small scale laboratory experiments (see fig. 1) to be quantitatively reproduced and can also be implemented in large scale models to improve hazard mitigation.

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