On Realization of Cinema Hall Fire Simulation Using Fire Dynamics Simulator

Currently known fire models are capable to describe fire dynamics in complex environments incorporating a wide variety of fire-related physical and chemical phenomena and utilizing large computational power of contemporary computers. In this paper, some issues related to realization of the simulation of fire in a cinema hall with sloping floor and curved ceiling furnished by upholstered seats modelled by FDS (Fire Dynamics Simulator) are discussed. The paper concentrates particularly on the impact of a computational meshes choice on resolving flow field and turbulence in the simulation and indicates problems related to parallelization of the calculation illustrated comparing sequential and parallel MPI calculation using 6 CPU cores. Results of the simulation described and their discussion demonstrate the ability of FDS simulation to capture main tendencies of smoke spread and to forecast the related safety risks realistically

Computing Aspects of Simulation Based on Conservation Laws Conducted on HPC Cluster

The large amount of computing resources required for the simulation of complex natural processes demands a thorough analysis of the efficiency of the calculations and the conditions that influence it. This study investigates computing aspects of fire simulation conducted on a compute cluster. Current fire simulators based on principles of computational fluid dynamics are capable to realistically model majority of complex phenomena related to fire. Fire simulations are highly computationally demanding itself, however, they often lead to extensive parametrical studies requiring high performance computing systems. Smoke stratification and visibility during fire in a road tunnel with two emergency lay-bys are investigated by parametrical study comprising of 24 fire scenarios with the tunnel geometry modifications and various heat release rates and fire locations. Main tendencies of smoke spread in the downstream lay-by are identified and their mutual interactions are analysed. The simulation efficiency of particular simulations is analysed and the reasons of their varied elapsed times are investigated. The analysis indicates that the main reason of this variability are different jet fans velocities influenced by simulation scenario settings

Stratification of fire smoke and testing aerosol in a road tunnel: computer simulation

The damage of the road tunnel during tunnel ventilation tests is prevented by using specific testing aerosol representing fire smoke. This study compares optical density profiles of aerosol and fire smoke using the well-known FDS simulation system, testing the suitability of aerosol to represent fire smoke realistically. The movement of aerosol and fire smoke downstream of the aerosol/fire source is investigated for a case of a 240 m long section of a road tunnel. Similarity of optical density profile for both cases under given conditions is confirmed. The influence of mesh resolution and the way of computational domain decomposition is evaluated as well. In case of fire smoke, the influence of domain decomposition and mesh resolution is very slight, while in case of aerosol it is more pronounced due to effect of relatively course numerical grid. The results support the hypothesis that the aerosol is suitable to represent the fire smoke for steady-state conditions occurring downstream of the fire in tunnel ventilation tests

An electrically actuated molecular toggle switch

Molecular electronics is considered a promising approach for future nanoelectronic devices. In order that molecular junctions can be used as electrical switches or even memory devices, they need to be actuated between two distinct conductance states in a controlled and reproducible manner by external stimuli. Here we present a tripodal platform with a cantilever arm and a nitrile group at its end that is lifted from the surface. The formation of a coordinative bond between the nitrile nitrogen and the gold tip of a scanning tunnelling microscope can be controlled by both electrical and mechanical means, and leads to a hysteretic switching of the conductance of the junction by more than two orders of magnitude. This toggle switch can be actuated with high reproducibility so that the forces involved in the mechanical deformation of the molecular cantilever can be determined precisely with scanning tunnelling microscopy

Six state molecular revolver mounted on a rigid platform

The rotation of entire molecules or large moieties happens at 100 ps time scales and the transition process itself is experimentally inaccessible to scanning probe techniques. However

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

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

Models of formation and spread of fire to increase safety of road tunnels

Fire safety of tunnels is an important issue which must be solved carefully during all phases of preparation, building and operation of each road tunnel. In this paper some particular results of a joint research project of the Institute of Informatics of Slovak Academy of Sciences and the University of Zilina are summarized. Some specific phenomena caused by fire in a real highway tunnel in Slovakia endangering safe evacuation of people from the tunnel are illustrated

Models of formation and spread of fire to increase safety of road tunnels

Fire safety of tunnels is an important issue which must be solved carefully during all phases of preparation, building and operation of each road tunnel. In this paper some particular results of a joint research project of the Institute of Informatics of Slovak Academy of Sciences and the University of Zilina are summarized. Some specific phenomena caused by fire in a real highway tunnel in Slovakia endangering safe evacuation of people from the tunnel are illustrated

A toolkit and methodology to support the collaborative development and reuse of engineering models

Engineering design is a knowledge intensive activity. Design is characterized as comprising a number of phases from requirements to detailed specification. Transitions between the design phases stem from decision-making processes supported both by generally available domain and design knowledge and from unique and original knowledge worth of recording for future reuse. The Clockwork project addresses the problems of representing, sharing and reusing knowledge in a collaborative design engineering environment. The Clockwork knowledge management methodology is supported by a web-based toolkit that allows designers to share, formally and informally annotate and reuse engineering models. Reuse is supported through the semantic search of engineering models and of the design rationale by which the engineering models were developed. The approach has been successfully deployed in two industrial organisations