scholarly journals Influence of slope and external temperature on smoke stratification in case of fire in bi-directional road tunnel

2018 ◽  
Vol 16 ◽  
pp. 02002
Author(s):  
Peter Weisenpacher ◽  
Jan Glasa ◽  
Lukas Valasek
Keyword(s):  
High Performance ◽  
Road Tunnel ◽  
Smoke Movement ◽  
Fire Dynamics ◽  
External Temperature ◽  
Computer Cluster ◽  
Parallel Version ◽  
Road Tunnels ◽  
Simulation Scenario ◽  
High Performance Computer

Jet fan ventilation strategy in case of fire in bi-directional road tunnels is focused on maintaining smoke stratification. There are several factors influencing stratification under specific conditions. In this paper smoke movement during a 5 MW fire in a 600 m long road tunnel is studied by computer simulation and the influence of slope and external temperature on smoke stratification is analysed. Calculations were performed on a high performance computer cluster using parallel version of Fire Dynamics Simulator. Smoke stratification upstream of the fire is maintained in every simulation scenario with the exception of declivous tunnel, in which buoyancy intensifies backlayering. The behaviour of the smoke movement downstream of the fire is more complex. In the case of horizontal tunnel the stratification is not maintained in the vicinity of the fire and region with untenable conditions expands downstream. In the tunnel with slope of -2° this expansion is accelerated, while in the tunnel with slope of 2° untenable conditions spread in opposite direction. The influence of exterior temperature higher than temperature inside the tunnel is relatively weak in horizontal tunnels; however, it becomes very important in sloping tunnels, especially downstream of the fire.

scholarly journals FDS simulation of smoke backlayering in emergency lay-by of a road tunnel with longitudinal ventilation

2021 ◽  
Vol 2090 (1) ◽  
pp. 012100
Author(s):  
P Weisenpacher ◽  
J Glasa ◽  
L Valasek ◽  
T Kubisova
Keyword(s):  
High Performance ◽  
Road Tunnel ◽  
Smoke Movement ◽  
Fire Dynamics ◽  
Computer Cluster ◽  
Longitudinal Ventilation ◽  
Smoke Spread ◽  
Fire Scenarios ◽  
Significant Length ◽  
High Performance Computer

Abstract This paper investigates smoke movement and its stratification in a lay-by of a 900 m long road tunnel by computer simulation using Fire Dynamics Simulator. The lay-by is located upstream of the fire in its vicinity. The influence of lay-by geometry on smoke spread is evaluated by comparison with a fictional tunnel without lay-by. Several fire scenarios with various tunnel slopes and heat release rates of fire in the tunnels without and with the lay-by are considered. The most significant breaking of smoke stratification and decrease of visibility in the area of the lay-by can be observed in the case of zero slope tunnel for more intensive fires with significant length of backlayering. Several other features of smoke spread in the lay-by are analysed as well. The parallel calculations were performed on a high-performance computer cluster.

Deterministic Risk Methodology for Road Tunnels

2008 ◽  
Author(s):  
Peter Vidmar ◽  
Stojan Petelin
Keyword(s):  
Safety Assessment ◽  
Calculated Data ◽  
Assessment Process ◽  
Strong Impact ◽  
Road Tunnel ◽  
Risk Matrix ◽  
Tunnel Length ◽  
Fire Dynamics ◽  
Road Tunnels ◽  
Ventilation Conditions

The definition of the deterministic approach in safety analyses arises from the need to understand the conditions that emerge during a fire accident in a road tunnel. The key factor of the tunnel operations during the fire is the ventilation, which during the initial phases of the fire have a strong impact on the evacuation of people and later on the access of the intervention units in the tunnel. The paper presents the use of the CFD model in the tunnel safety assessment process. The set-up of the initial and boundary conditions and the requirement for grid density found from validation tests of an FDS (Fire Dynamics Simulator) is used to prepare three kinds of fire scenarios, 20MW, 50MW and 100MW, with different ventilation conditions; natural, semi transverse, transverse and longitudinal ventilation. The observed variables, soot density and temperature, are presented in minutes time steps through the entire tunnel length. Comparing the obtained data in a table allows the analyses of the ventilation conditions for different heat releases from fires. The second step is to add additional criteria of human behaviour inside the tunnel (evacuation) and human resistance to the elevated gas concentrations and temperature. What comes out is a fully deterministic risk matrix that is based on the calculated data where the risk is ranged on five levels, from the lowest to a very dangerous level. The deterministic risk matrix represents the alternative to a probabilistic safety assessment methodology, wherein the fire risk is represented in detail and the CFD (Computational Fluid Dynamics) model results are physically correct.

Using Parallel Computing in Queueing Network Simulation

2016 ◽  
Vol 685 ◽  
pp. 943-947 ◽  
Author(s):  
Roman Mesheryakov ◽  
Alexander Moiseev ◽  
Anton Demin ◽  
Vadim Dorofeev ◽  
Vasily Sorokin
Keyword(s):  
Parallel Computing ◽  
Queueing Networks ◽  
High Performance ◽  
High Efficiency ◽  
Discrete Event ◽  
Queueing Network ◽  
Object Oriented Programming ◽  
Computer Cluster ◽  
General Network ◽  
High Performance Computer

The paper is devoted to the simulation of queueing networks on high performance computer clusters. The objective is to develop a mathematical model of queueing network and simulation approach to the modelling of the general network functionality, as well as to provide a software implementation on a high-performance computer cluster. The simulation is based on a discrete-event approach, object oriented programming, and MPI technology. The model of the queueing networks simulation system was developed as an application that allows a user to simulate networks of rather free configuration. The experiments on a high performance computer cluster emphasize the high efficiency of parallel computing.

scholarly journals Improving computational efficiency of GLUE method for hydrological model uncertainty and parameter estimation using CPU-GPU hybrid high performance computer cluster

2021 ◽  
Author(s):  
Depeng Zuo ◽  
Guangyuan Kan ◽  
Hongquan Sun ◽  
Hongbin Zhang ◽  
Ke Liang
Keyword(s):  
Parameter Estimation ◽  
Computational Efficiency ◽  
High Performance ◽  
Large Scale ◽  
Hydrological Model ◽  
Computer Cluster ◽  
Comparison Results ◽  
High Performance Computer ◽  
Glue Method ◽  
Generalized Likelihood Uncertainty Estimation

Abstract. The Generalized Likelihood Uncertainty Estimation (GLUE) method has been thrived for decades, huge number of applications in the field of hydrological model have proved its effectiveness in uncertainty and parameter estimation. However, for many years, the poor computational efficiency of GLUE hampers its further applications. A feasible way to solve this problem is the integration of modern CPU-GPU hybrid high performance computer cluster technology to accelerate the traditional GLUE method. In this study, we developed a CPU-GPU hybrid computer cluster-based highly parallel large-scale GLUE method to improve its computational efficiency. The Intel Xeon multi-core CPU and NVIDIA Tesla many-core GPU were adopted in this study. The source code was developed by using the MPICH2, C++ with OpenMP 2.0, and CUDA 6.5. The parallel GLUE method was tested by a widely-used hydrological model (the Xinanjiang model) to conduct performance and scalability investigation. Comparison results indicated that the parallel GLUE method outperformed the traditional serial method and have good application prospect on super computer clusters such as the ORNL Summit and Sierra of the TOP500 super computers around the world.

Improved 3-D reconstruction using stereo computer graphics and multiple tilt EM images

1995 ◽  
Vol 53 ◽  
pp. 630-631
Author(s):  
Lee D. Peachey ◽  
Lou Fodor ◽  
John C. Haselgrove ◽  
Stanley M. Dunn ◽  
Junqing Huang
Keyword(s):  
Computer Graphics ◽  
High Performance ◽  
Transverse Section ◽  
Three Dimensional ◽  
Stereo Pair ◽  
3D Reconstructions ◽  
Video Cameras ◽  
Biological Objects ◽  
Microscope Images ◽  
High Performance Computer

Stereo pairs of electron microscope images provide valuable visual impressions of the three-dimensional nature of specimens, including biological objects. Beyond this one seeks quantitatively accurate models and measurements of the three dimensional positions and sizes of structures in the specimen. In our laboratory, we have sought to combine high resolution video cameras with high performance computer graphics systems to improve both the ease of building 3D reconstructions and the accuracy of 3D measurements, by using multiple tilt images of the same specimen tilted over a wider range of angles than can be viewed stereoscopically. Ultimately we also wish to automate the reconstruction and measurement process, and have initiated work in that direction.Figure 1 is a stereo pair of 400 kV images from a 1 micrometer thick transverse section of frog skeletal muscle stained with the Golgi stain. This stain selectively increases the density of the transverse tubular network in these muscle cells, and it is this network that we reconstruct in this example.

scholarly journals Should We Expect a Disastrous Fire Accident in an Urban Road Tunnel? Literature Data Review and a Case Study for Selected Tunnels in Poland

2021 ◽  
Vol 13 (11) ◽  
pp. 6172
Author(s):  
Krystian Szewczyński ◽  
Aleksander Król ◽  
Małgorzata Król
Keyword(s):  
Time Horizon ◽  
Road Traffic ◽  
Traffic Intensity ◽  
Road Tunnel ◽  
Urban Road ◽  
Road Tunnels ◽  
High Uncertainty ◽  
Fire Outbreak ◽  
Fire Accident

Urban road tunnels are a reasonable remedy for inconvenience due to congested road traffic. However, they bring specific threats, especially those related to the possibility of fire outbreak. This work is a case study for selected urban road tunnels. Considering tunnel specificity, road traffic intensity, and structure and based on the literature data for vehicle fire probability, the chances of a fire accident were estimated for selected tunnels in Poland. It was shown that low power tunnel fires could be expected in the 10–20-year time horizon. Although such threats cannot be disregarded, tunnel systems are designed to cope with them. The chances of a disastrous fire accident were estimated as well. Such events can occur when an HGV with flammable goods or a tanker are involved. Such accidents are fortunately very rare, but, on the other hand, that is the reason why the available data are scanty and burdened with high uncertainty. Therefore, a discussion on the reliability of the obtained results is also provided.

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