Numerical Simulation of Pyroclastic Flow at Mt. Semeru in 2002

2019 ◽  
Vol 14 (1) ◽  
pp. 116-125
Author(s):  
Makoto Shimomura ◽  
Wilfridus F. S. Banggur ◽  
Agoes Loeqman ◽  
◽  
Keyword(s):  
Numerical Simulation ◽  
Friction Factor ◽  
Pyroclastic Flow ◽  
Sudden Change ◽  
Simulation Method ◽  
Active Volcano ◽  
Flow Path ◽  
Pyroclastic Flows ◽  
Set Up ◽  
The Individual

Mt. Semeru (3676 m asl.) is an active volcano in Indonesia. Mt. Semeru has a specific topography i.e., a large straight scar in its south-east flank. The geometry of the scar is approx. 2 km in length and 300–500 m width. The scar is connected to three major drainage channels: the Kobokan River, the Kembar River, and the Bang River. On December 29, 2002, a pyroclastic flow (PF) with an approximate volume of 3.25 × 106m3was generated and it traveled 9–11 km along the Bang River. This pyroclastic flow was the largest among the ones generated from 2002–2003 eruptions of Mt. Semeru. All prior recorded pyroclastic flows traveled 1–2.5 km along the Kembar channel. Thus, this pyroclastic flow suddenly changed its flow path, and it traveled more than three times longer than its antecedents. To investigate the cause of the sudden change, a simulated reproduction of this pyroclastic flow was carried out by employing the numerical simulation method proposed by Yamashita and Miyamoto (1993). Due to the uncertainty of the volume of each pyroclastic flow and the temporal change of deposition thickness, a total of 12 simulation cases were set up, with variations in the number of sequence events, the duration of inflow at the upper reach of the flow, and the inter-granular friction factor. The simulation results showed that to explain the sudden change in flow path, the Kembar channel, around 3 km from the vent, has to be buried by antecedent pyroclastic flows. Furthermore, the individual volumes of the prior flows must be less than 0.25–1× 106m3, with an inflow duration of less than 1 min. The friction factor must be set to be 0.5. By using the most acceptable case, the simulated pyroclastic flows were in good agreement with observed results. The results implied that careful investigation and continuous monitoring of the area at 1500–2000 m asl. on the south-east flank of Mt. Semeru are important to prepare for future pyroclastic flows.

Heat Exchange Calculation of a Regenerative Air Heater with Numerical Simulation Method

2013 ◽  
Vol 860-863 ◽  
pp. 1416-1419
Author(s):  
Ri Guang Wei ◽  
Zhen Xiao Qu ◽  
Jian Qiang Gao
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Calculation Model ◽  
Design Parameters ◽  
Practical Calculation ◽  
Air Preheater ◽  
Air Heater ◽  
Pulverized Coal Boiler ◽  
Set Up ◽  
Coal Boiler

According to the structure and working principle of rotary air preheater,the heat transfer calculation model is set up with reasonable simplification. Combining with the design parameters of the rotary air preheater of a 400 t/h pulverized coal boiler unit ,the results of practical calculation show that the said thermodynamic calculation method not only has higher precision of calculation,but also can get the temperature distributions of the gas, air and heat surface in each cross-section of the rotary air preheater. The result of numerical simulation calculation tallies well with the original designed data. It can be used for the heat calculation both two-sectorial and three-sectorial air heater; it can be used for performance analysis of the regenerative air heater.

Numerical Simulation of Mt. Merapi Pyroclastic Flow in 2010

2019 ◽  
Vol 14 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Makoto Shimomura ◽  
Raditya Putra ◽  
Niken Angga Rukmini ◽  
Sulistiyani ◽  
◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Friction Factor ◽  
Pyroclastic Flow ◽  
Influencing Factor ◽  
Flow Characteristics ◽  
Suitable Condition ◽  
Pyroclastic Material ◽  
Inundation Area ◽  
Wide Range ◽  
Granular Friction

A pyroclastic flow is one of the most dangerous hazardous phenomena. To escape a pyroclastic flow, the influenceable area must be evacuated before the flow occurs. Therefore, to predict the inundation area of a pyroclastic flow is important, and numerical simulation is a helpful tool in this prediction. This study simulated a pyroclastic flow by reproducing the pyroclastic flow of Mt. Merapi that occurred in 2010. However, necessary detailed information of the flow to conduct the simulation, such as total volume and the property of the pyroclastic flow material, flow rate, etc., were not available. Therefore, 20 simulations were conducted, varying the important conditions, such as the volume of pyroclastic material, inter-granular friction factor, and duration of the flow. The results showed that the volume of the pyroclastic material and inter-granular friction factor strongly control the flow characteristics. However, the friction factor does not result in a wide range of values; therefore, volume is the most influencing factor. The most suitable condition is a total volume of pyroclastic material of 30 × 106m3, a 5 min duration of flow, and a 0.6 friction factor.

Numerical Simulation on Blasting Fume Diffusion in Blind Roadway with FLUENT

2013 ◽  
Vol 663 ◽  
pp. 655-660
Author(s):  
Zhen Hua Xie ◽  
Zheng Lan Yuan ◽  
Yu Zhang
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Mining Area ◽  
Computational Grids ◽  
Actual Situation ◽  
Forced Ventilation ◽  
Iron Mine ◽  
Effective Ventilation ◽  
Set Up ◽  
And Diffusion

Aiming at the generation of blasting fume in underground blind roadway, numerical simulation method was taken to obtain the diffusion law of the blasting fume. In accordance with the actual situation in Shachang mining area of Shouyun iron mine, the physical model and mathematical model were set up, computational grids were divided, and the boundary condition was established. The diffusion law of blasting fume and the completion time under different explosives dosage were simulated by Fluent. The laws of blasting fume diffusion and diffusion time changing with the amount of explosive in local fan forced ventilation were obtained. The results can provide a theoretical basis for the research of a reasonable and effective ventilation manner of blind roadway.

Three-dimensional numerical simulation of velocity field distribution in an oxy-coal combustor-melter-separator furnace

2021 ◽  
Vol 118 (5) ◽  
pp. 510
Author(s):  
Yao-zong Shen ◽  
Kai Zhao ◽  
Zheng Kong ◽  
Yu-zhu Zhang ◽  
Yan Shi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Velocity Field ◽  
Velocity Distribution ◽  
Molten Pool ◽  
Dead Zone ◽  
Sudden Change ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Simulation Method ◽  
Distribution Area

In view of the influence of tuyere layout change on velocity field in oxy-coal combustor-melter-separator furnace, three-dimensional numerical simulation method was used to compare the distribution of velocity field in the furnace under different tuyere layout. The purpose is to explore the influence of the velocity distribution on the molten pool flow in the process of multi-tuyere injection. It is shown that the maximum velocity of the upper and lower tuyeres is 60 m/s and 50 m/s. And the change of tuyere has a significant effect on the velocity distribution in the molten pool, and the sudden change of velocity near the tuyere will trigger a certain scale of gyratory zone. In addition, the change of tuyere arrangement will result in the concentration of velocity distribution in the molten pool and the increase of flow dead zone, while the change of tuyere spacing will not only promote the increase of flow dead zone, but also reduce the velocity distribution area.

Numerical Simulation of Stress Wave Propagation Induced by Cut Blasting in Multi-Media

2012 ◽  
Vol 249-250 ◽  
pp. 22-25
Author(s):  
Guo Liang Yang ◽  
Ren Shu Yang ◽  
Chuan Huo ◽  
Yu Long Che
Keyword(s):  
Numerical Simulation ◽  
Stress Wave ◽  
Strong Shock ◽  
Simulation Method ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Weathered Rock ◽  
Plastic Damage ◽  
Multi Media ◽  
Set Up

Explosive blasting in rock and other media could induce strong shock wave. Near blasting zone, the blasting energy mainly break rock. Slightly far away from borehole, the blasting energy induces plastic damage. Farther afield, this kind of energy presents elastic deformation. In cut blasting, multi-boreholes initiate at the same time, multi-column stress waves occur superimpose and converge. Especially in multi-media, this process is extremely complex. Adopt numerical simulation method, set up multi-media model, which include weathered rock, highly weathered rock and plain fill. This paper simulated the propagation process of stress wave in these medias. Revealed the propagation mechanics of stress wave.

Numerical Simulation of Ozone Oxidation on Oily Wastewater

2011 ◽  
Vol 71-78 ◽  
pp. 2721-2726
Author(s):  
Meng Fu Zhu ◽  
Cheng Deng ◽  
Xiu Dong You ◽  
Hong Bo Su ◽  
Ping Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Oil Content ◽  
Simulation Method ◽  
Pollutant Removal ◽  
Oily Wastewater ◽  
Theory Analysis ◽  
Reaction Equation ◽  
Simulation Results ◽  
Set Up

A simulation method was presented based on the theory analysis and ozone reaction equation. The preliminary mathematical models of ozonation correlative to oily pollutant removal were set up by numerical simulation. The ozonation models implied removal ratio of oil related to reaction time, ozone dosage and initial oil content. The simulation results were consistent with the experimental data.

Numerical Simulation and Analysis of Sand-Shale Ratio of Bedrock Impacting Mining Subsidence

2014 ◽  
Vol 962-965 ◽  
pp. 1195-1200
Author(s):  
Shi Jie Song ◽  
Xiao Guang Zhao ◽  
Nian Zhang ◽  
Lu Zhao
Keyword(s):  
Numerical Simulation ◽  
Layered Structure ◽  
Simulation Method ◽  
Mining Area ◽  
Mining Subsidence ◽  
Overburden Rock ◽  
Coal Mining Area ◽  
Basic Law ◽  
Set Up ◽  
Coal Measures

Significant geological factor of coal occurrence is layered structure of coal measures overburden rock, and bedrock sand-shale ratio is a key element of coal measures overburden rock layered structure. On the background of geological occurrence conditions of 2-2 coal in Yushen coal mining area, the sandstone layer, sandstone average thickness and sand-shale ratio are taken as variables to build the 18 different types of layered structure models. On this basis, basic law of coal measures bedrock sand-shale ratios which is a key characteristic of layered structure impacting mining subsidence is mainly studied by using numerical simulation method. The results show that: firstly, in spite of any condition of sandstone layer coefficient subsidence coefficient always decrease with the increase of sand-shale ratios. However, the effect of sand-shale ratios on subsidence coefficient continuously decreased with the increasing of sandstone layer coefficient. Secondly, when the sandstone layer coefficient is less than 70%, the different sand-shale ratios have significant influence on the subsidence coefficient, and when the sandstone layer coefficient is more than 90%, subsidence coefficients corresponding to different sand-shale ratios show obvious convergence characteristics. The gap between each other is only 1%~2%. Thirdly, taking the subsidence coefficient corresponding to the sand-shale ratio is 6:4 as reference, the curves about the rate of decrease in subsidence coefficient is set up when the sand-shale ratio is 7:3 or 8:2, and the fitting equations are presented on the basis of Log3P1 mathematical model.

Numerical Simulation of the Urine Flow in a Stented Ureter

2006 ◽  
Vol 129 (2) ◽  
pp. 187-192 ◽  
Author(s):  
Jimmy C. K. Tong ◽  
Ephraim M. Sparrow ◽  
John P. Abraham
Keyword(s):  
Numerical Simulation ◽  
Rational Design ◽  
Numerical Solutions ◽  
Simulation Method ◽  
Flow Path ◽  
Urine Flow ◽  
Flow Through ◽  
Pass Through ◽  
First Time ◽  
Bladder Urine

When a stent is implanted in a blocked ureter, the urine passing from the kidney to the bladder must traverse a very complicated flow path. That path consists of two parallel passages, one of which is the bore of the stent and the other is the annular space between the external surface of the stent and the inner wall of the ureter. The flow path is further complicated by the presence of numerous pass-through holes that are deployed along the length of the stent. These holes allow urine to pass between the annulus and the bore. Further complexity in the pattern of the urine flow occurs because the coiled “pig tails,” which hold the stent in place, contain multiple ports for fluid ingress and egress. The fluid flow in a stented ureter has been quantitatively analyzed here for the first time using numerical simulation. The numerical solutions obtained here fully reveal the details of the urine flow throughout the entire stented ureter. It was found that in the absence of blockages, most of the pass-through holes are inactive. Furthermore, only the port in each coiled pig tail that is nearest the stent proper is actively involved in the urine flow. Only in the presence of blockages, which may occur due to encrustation or biofouling, are the numerous pass-through holes activated. The numerical simulations are able to track the urine flow through the pass-through holes as well as adjacent to the blockages. The simulations are also able to provide highly accurate results for the kidney-to-bladder urine flow rate. The simulation method presented here constitutes a powerful new tool for rational design of ureteral stents in the future.

Numerical Simulation of Historical Pyroclastic Flows of Merapi (1994, 2001, and 2006 Eruptions)

2019 ◽  
Vol 14 (1) ◽  
pp. 90-104
Author(s):  
Niken Angga Rukmini ◽  
Sulistiyani ◽  
Makoto Shimomura ◽  
◽  
Keyword(s):  
Numerical Simulation ◽  
Pyroclastic Flow ◽  
High Speed ◽  
Pyroclastic Flows ◽  
Past Century ◽  
Rock Fragments ◽  
The Past ◽  
Dome Collapse ◽  
And Behavior ◽  
Lava Dome Collapse

Merapi has become one of the most enticing volcanoes due to its activity over the past century. Although we have to agree that the 2010 VEI = 4 (Volcanic Explosivity Index, [1]) eruption is the greatest in its recorded history, Merapi is more famous for its shorter cycle of smaller scale, making it one of the most active volcanoes on Earth. Many mechanisms are involved in an eruption, and pyroclastic flow is the most dangerous occurrence in terms of volcanic hazard. A pyroclastic flow is defined as a high-speed avalanche consisted of high temperature mixture of rock fragments and gas, resulted from lava dome collapse and/or gravitational column collapse. Researchers have studied Merapi’s history and behavior, and numerical simulations are an important tool for future hazard mitigation. By utilizing numerical simulation on basal part of pyroclastic flow, we investigated the applicability of the simulation on pyroclastic flows from historical eruptions of Merapi (1994, 2001, and 2006). Herein, we present a total of 32 simulations and discuss the areas affected by pyroclastic flows and the factors that affect the simulation results.

Numerical Simulation of Damage and Deformation Characteristics of Rock Mass with Transfixion Joint

2013 ◽  
Vol 405-408 ◽  
pp. 369-372
Author(s):  
Lei Wang ◽  
Jiang Yu ◽  
Jian Xin Han
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Strain Curve ◽  
Simulation Method ◽  
Joint Surface ◽  
Deformation Characteristics ◽  
Stress Strain Curve ◽  
Deformation Parameters ◽  
Strength And Deformation ◽  
Set Up

Use FLAC3D, the interface command to define joint surface, set up rock mass models with 15 °, 30 °, 60 °, etc. different dip joint, and in accordance with the laboratory test data of rock and joint surface for a variety of strength and deformation parameters setting, carries on the numerical simulation of uniaxial compression. Got failure mode, plastic zone evolution and the stress strain curve of rock mass with different dip joint, and the result compared with the actual test has a higher similarity, to prove the feasibility of the numerical simulation method.

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