scholarly journals A Scheme of Computational Time Reduction on Back-End Server Using Computational Grid

Author(s):  
Seong-Pyo Hong ◽  
Seung-Jo Han
2018 ◽  
Vol 40 ◽  
pp. 06023
Author(s):  
Martin Bruwier ◽  
Pierre Archambeau ◽  
Sébastien Erpicum ◽  
Michel Pirotton ◽  
Benjamin Dewals

Anisotropic porosity shallow-water models are used to take into account detailed topographic information through porosity parameters multiplying the various terms of the shallow-water equations. A storage porosity is assigned to each cell to reflect the void fraction in the cell and a conveyance porosity is used at each edge to reproduce the impact of subgrid obstacles on the flux terms. To guaranty the numerical stability, the time step depends on the value of the porosity parameters. This may hamper severely the computational efficiency in the presence of cells with low values of storage porosity. Cartesian grids are particularly sensitive to such a case since the meshing stems directly from the choice of the grid size. In this paper, this problem is addressed by using an original merging technique consisting in merging cells with a storage porosity lower than a threshold value with neighbouring cells. The model was tested for modelling a prismatic channel with different orientations between the Cartesian computational grid and the channel direction. The results show that the standard anisotropic porosity model (without merging) improves the reproduction of the flow characteristics; but at the cost of a significantly higher computational time. In contrast, the computational time is drastically reduced and the accuracy preserved when the merging technique is used with the porosity model.


Author(s):  
Yutaro Okamoto ◽  
◽  
Chinthaka Premachandra ◽  
Kiyotaka Kato

Automatic road obstacle detection is one of the significant problem in Intelligent Transport Systems (ITS). Many studies have been conducted for this interesting problem by using on-vehicle cameras. However, those methods still needs a dozens ofmillisecondsfor image processing. To develop the quick obstacle avoidance devices for vehicles, further computational time reduction is expected. Furthermore, regarding the applications, compact hardware is also expected for implementation. Thus, we study on computational time reduction of the road obstacle detection by using a small-type parallel image processor. Here, computational time is reduced by developing an obstacle detection algorithm which is appropriated to parallel processing concept of that hardware. According to the experimental evaluation of the new proposal, we could limit computational time for eleven milliseconds with a good obstacle detection performance.


2009 ◽  
Vol 2009 (0) ◽  
pp. _423-1_-_423-5_
Author(s):  
Youhei AZUMA ◽  
Kazuhiko ADACHI ◽  
Yu HASEGAWA ◽  
Atsushi FUJITA ◽  
Eiji KOHMURA

2018 ◽  
Vol 33 (1) ◽  
pp. 281-289 ◽  
Author(s):  
Bert Hannon ◽  
Peter Sergeant ◽  
Luc Dupre

2017 ◽  
Vol Vol 159 (A2) ◽  
Author(s):  
J Yao

The flow around a full scale (FS) ship can be simulated by mean s of Reynolds Averaged Naiver Stokes (RANS) method, which provides a way to obtain more knowledge about scale effect s on ship hydrodynamics. In this work, the viscous flow around a static drift tanker in full scale is simulated by using the RANS solver based on the open source platform OpenFOAM. The 𝑘−𝜔 SST model is employed to approximate the eddy viscosity. To reduce computational time, wall function approach is applied for the FS simulation. The flow around the ship in model scale is simulated as well, but without using any wall function, i.e. using Low Reynolds number mode. In order to verify the computations, de-tailed studies on the computational grid including investigation of the sensitivity of computed forces to 𝑦+ (dimension-less distance of first grid point to wall) and grid dependency study are carried out. The computed forces are compared with available measured data The scale effect s are analysed and discussed by comparisons.


2017 ◽  
Vol 105 ◽  
pp. 34-42
Author(s):  
Angel Martín Furones ◽  
Ana Belén Anquela Julián ◽  
Alejandro Dimas-Pages ◽  
Fernando Cos-Gayón

Sign in / Sign up

Export Citation Format

Share Document