Parallel CFD simulation of flow in a 3D model of vibrating human vocal folds

2013 ◽  
Vol 80 ◽  
pp. 290-300 ◽  
Author(s):  
Petr Šidlof ◽  
Jaromír Horáček ◽  
Václav Řidký
Keyword(s):  
3D Model ◽  
Cfd Simulation ◽  
Vocal Folds ◽  
Parallel Cfd

A Time-Parallel CFD Approach for Unsteady Combustor Flow Analysis and Design Optimization

2012 ◽  
Author(s):  
Moresh J. Wankhede ◽  
Neil W. Bressloff ◽  
Andy J. Keane
Keyword(s):  
Flow Field ◽  
Domain Decomposition ◽  
Design Optimization ◽  
Cfd Simulation ◽  
Simulation Method ◽  
Spatial Domain ◽  
Parallel Simulation ◽  
Analysis And Design ◽  
Temporal Domain ◽  
Parallel Cfd

Computational fluid dynamics (CFD) simulations to predict and visualize the reacting flow dynamics inside a combustor require fine resolution over the spatial and temporal domain, making them computationally very expensive. The traditional time-serial approach for setting up a parallel combustor CFD simulation is to divide the spatial domain between computing nodes and treat the temporal domain sequentially. However, it is well known that spatial domain decomposition techniques are not very efficient especially when the spatial dimension (or mesh count) of the problem is small and a large number of nodes are used, as the communication costs due to data parallelism becomes significant per iteration. Hence, temporal domain decomposition has some attraction for unsteady simulations, particularly on relatively coarse spatial meshes. The purpose of this study is two-fold: (i), to develop a time-parallel CFD simulation method and apply it to solve the transient reactive flow-field in a combustor using an unsteady Reynolds-averaged Navier Stokes (URANS) formulation in the commercial CFD code FLUENT™ and (ii) to investigate its benefits relative to a time-serial approach and its potential use for combustor design optimization. The results show that the time-parallel simulation method correctly captures the unsteady combustor flow evolution but, with the applied time-parallel formulation, a clear speed-up advantage, in terms of wall-clock time, is not obtained relative to the time-serial approach. However, it is clear that the time-parallel simulation method provides multiple stages of transient combustor flow-field solution data whilst converging towards a final converged state. The availability of this resulting data could be used to seed multiple levels of fidelity within the framework of a multi-fidelity co-Kriging based design optimization strategy. Also, only a single simulation would need to be setup from which multiple fidelities are available.

Airflow Characterization Combined With 3D Reconstruction of Rabbit Vocal Cord Based on In-Vivo Phonatory Experiments

2020 ◽  
Author(s):  
Zhipeng Lou ◽  
Junshi Wang ◽  
James J. Daniero ◽  
Haibo Dong ◽  
Jinxiang Xi
Keyword(s):  
3D Reconstruction ◽  
Vocal Cord ◽  
Vocal Fold ◽  
High Speed ◽  
3D Model ◽  
Vocal Folds ◽  
Computational Effort ◽  
Immersed Boundary ◽  
Vibration Modes

Abstract In this paper, a numerical approach combined with experiments is employed to characterize the airflow through the vocal cord. Rabbits are used to perform in vivo magnetic resonance imaging (MRI) experiments and the MRI scan data are directly imposed for the three-dimensional (3D) reconstruction of a 3D high-fidelity model. The vibration modes are observed via the in vivo high-speed videoendoscopy (HSVM) technique, and the time-dependent glottal height is evaluated dynamically for the validation of the 3D reconstruction model. 72 sets of rabbit in vivo high-speed recordings are evaluated to achieve the most common vibration mode. The reconstruction is mainly based on MRI data and the HSVM records are supporting and validate the 3D model. A sharp-interface immersed-boundary-method (IBM)-based compressible flow solver is employed to compute the airflow. The primary purpose of the computational effort is to characterize the influence of the vocal folds that applied to the airflow and the airflow-induced phonation. The vocal fold kinematics and the vibration modes are quantified and the vortex structures are analyzed under the influence of vocal folds. The results have shown significant effects of the vocal fold height on the vortex structure, vorticity and velocity. The reconstructed 3D model from this work helps to bring insight into further understanding of the rabbit phonation mechanism. The results provide potential improvement for diagnosis of human vocal fold dysfunction and phonation disorder.

scholarly journals AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Ren Xiaoguang ◽  
Xu Xinhai
Keyword(s):  
Cfd Simulation ◽  
Massively Parallel ◽  
Optimization Scheme ◽  
Total Execution Time ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Application Characteristics ◽  
Asynchronous Pipeline ◽  
User Friendly ◽  
Parallel Cfd

Computational fluid dynamics (CFD) simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO) optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. InAP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework ofAP-IOand implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on theTianhe-2supercomputer demonstrate thatAP-IOcan achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.

Emission Performance of a Diesel Engine with Pressure-Wave Supercharger

2011 ◽  
Vol 383-390 ◽  
pp. 6168-6173
Author(s):  
Yan Lei ◽  
Hong Guang Zhang ◽  
Da Sen Zhou ◽  
Xiao Lei Bai
Keyword(s):  
Diesel Engine ◽  
Experimental Test ◽  
Pressure Wave ◽  
Engine Speed ◽  
3D Model ◽  
Cfd Simulation ◽  
Test Results ◽  
Turbocharged Diesel Engine ◽  
Emission Performance ◽  
Simulation Results

Pressure-wave supercharger (PWS) is one technical way to boost the engine intake air pressure. PWS has several advantages such as less emission (especially NOx emission), rapid response when load changes, higher torque even at low engine speed. In this research a 493 diesel engine is charged by a pressure-wave supercharger (PWS). The emission performance of the PWS diesel engine is mainly investigated. Together with experimental test, the CFD simulation is completed basing on a 3D model of the PWS rotor channel. The CFD simulation results show that the inner EGR phenomenon happens especially when PWS runs at middle PWS rotational speed with part load. The test results demonstrate that the PWS diesel engine performs well with less NOx and soot emissions than the turbocharged diesel engine.

Multiphase CFD Simulation of Photogrammetry 3D Model for UAV Crop Spraying

2019 ◽  
pp. 812-822 ◽  
Author(s):  
Héctor Guillermo Parra ◽  
Victor Daniel Angulo Morales ◽  
Elvis Eduardo Gaona Garcia
Keyword(s):  
3D Model ◽  
Cfd Simulation ◽  
Multiphase Cfd

scholarly journals CFD Simulation of Defogging Effectivity in Automotive Headlamp

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2609
Author(s):  
Michal Guzej ◽  
Martin Zachar
Keyword(s):  
Traffic Safety ◽  
3D Model ◽  
Cfd Simulation ◽  
Dew Point ◽  
Dynamics Simulation ◽  
Ambient Conditions ◽  
Computational Fluid Dynamics Simulation ◽  
The Past ◽  
Direct Exposure ◽  
Technical Solutions

In the past decade, the condensation of internal air humidity in automotive headlamps has become more prevalent than ever due to the increased usage of a new light source—LEDs. LEDs emit far less heat than previously-used halogen lamps, which makes them far more susceptible to fogging. This fogging occurs when the internal parts of the headlamp fall to a temperature below the dew point. The front glass is most vulnerable to condensation due to its direct exposure to ambient conditions. Headlamp fogging leads to a decrease in performance and the possibility of malfunctions, which has an impact not only on the functional aspect of the product’s use but also on traffic safety. There are currently several technical solutions available which can determine the effectivity of ventilation systems applied for headlamp defogging. Another approach to this problem may be to use a numerical simulation. This paper proposes a CFD (computational fluid dynamics) simulation with a slightly simplified 3D model of an actual headlamp, which allows simulation of all the phenomena closely connected with fluid flow and phase change. The results were validated by real experiments on a special fogging–defogging test rig. This paper compares three different simulations and their compliance with real experiments.

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