Numerical Study of Depressurization Rate during Blowdown Based on Lumped Model Analysis

1984 ◽  
Vol 21 (12) ◽  
pp. 931-941 ◽  
Author(s):  
Takashi IKEDA ◽  
Atsuo YAMANOUCHI ◽  
Isao SUMIDA
Keyword(s):  
Numerical Study ◽  
Model Analysis ◽  
Lumped Model

scholarly journals Numerical Study of Lymph Mechanics

2021 ◽  
Author(s):  
◽  
Daniel J. Watson
Keyword(s):  
Lymphatic System ◽  
Numerical Study ◽  
Patient Specific ◽  
Single Subject ◽  
3D Analysis ◽  
Large Network ◽  
Lumped Model ◽  
Biphasic Model ◽  
Lymphatic Valve ◽  
Scale Modelling

Methods taken from engineering and computer science were applied to the lymphatic system. Starting with a 3D analysis of a single subject-specific lymphatic valve. A mechanism was presented to explain previous experimental results showing the effect of trans-mural pressure on the pressure required to close lymphatic valves. The impor-tance of wall motion in future FSI studies of lymphatic valve dynamics were identified. Previous approaches to lumped modelling of the lymphatic system were considered and modifications were proposed. A less-idealised valve model, incorporating trans-mural dependent bias, was proposed as well as a method of allowing self-organised contrac-tion through a stretch-dependent frequency of contraction. A network of the superficial lymphatics of the upper-limb was reconstructed from an anatomical sketch. The net-work was used in conjunction with the lumped model to produce a 421 vessel lymphatic model consisting of 17,706 lymphangions. Several issues which impede large network scale modelling of the lymphatic system are identified. A simplified patient-specific biphasic model of lymphoedema was proposed and used to develop a novel shape-based metric for lymphoedema. A statistically significant relationship between the metric and the presence of lymphoedema was found.

Lumped-Model Analysis of Microcircuit Vulnerability

1968 ◽  
Vol 15 (6) ◽  
pp. 271-278 ◽  
Author(s):  
J. P. Raymond ◽  
W. W. Chang ◽  
R. E. Budris
Keyword(s):  
Model Analysis ◽  
Lumped Model

Numerical Analysis of the Sugarcane Bagasse Drying by Cyclone

2018 ◽  
Vol 20 ◽  
pp. 106-123
Author(s):  
J.A. Ribeiro de Souza ◽  
Severino Rodrigues de Farias Neto ◽  
E. Santana de Lima ◽  
A.G. Barbosa de Lima ◽  
H. Monteiro Lopes
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Heat And Mass Transfer ◽  
Sugarcane Bagasse ◽  
Numerical Study ◽  
Flow Direction ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Lagrangian Model ◽  
Lumped Model

Drying is a simultaneous process of heat and mass transfer and dimensional changes. In recent years, cyclones have been used as a modern drying technology. In this sense, this research proposes a numerical study to describe drying of sugarcane bagasse, using the cyclone as dryer. Herein, it was adopted the Eulerian-Lagrangian model in steady state. The Reynolds stress model was considered to describe turbulence of the gas phase, while a transient lumped model was used to describe heat and mass transfer on the particulate phase (sugarcane bagasse). Particles were considered with irregular shape, composed of a binary mixture (solid part and water). The solution of the proposed model was obtained using the commercial software Ansys CFX 12. Results of the moisture content, temperature, dimension variation, and paths of particles, as well as velocity, pressure, and temperature distributions of the gas phase inside the cyclone are presented and analyzed. It has been found that the obtained components for axial and tangential velocity inside the cyclone are in good agreement with experimental data available in the literature, and that the drying kinetics, heating, dimensional variations, and residence time of particles are affected by the velocity of the gas phase, velocity of the particles, and the flow direction of gas and particles at the entrance of the feed duct.

scholarly journals Dynamic behaviour and stability analysis of a compensated aerostatic pad

2021 ◽  
Vol 312 ◽  
pp. 05003
Author(s):  
Federico Colombo ◽  
Luigi Lentini ◽  
Terenziano Raparelli ◽  
Andrea Trivella ◽  
Vladimir Viktorov
Keyword(s):  
Dynamic Behaviour ◽  
Numerical Study ◽  
Dynamic Performance ◽  
Low Friction ◽  
Lumped Model ◽  
Positioning Systems ◽  
Diaphragm Valve ◽  
Bearing Stiffness ◽  
The Stability ◽  
Stiffness And Damping

Thanks to their low friction, aerostatic pads have important applications in precision positioning systems and linear guides. A simple and cheap solution to increase the static stiffness of aerostatic pads is to add a proper designed pneumatic valve to regulate the air flow supplied to the bearing. However, integrating aerostatic pads with additional devices can reduce its dynamic performance. This paper presents a numerical study on the dynamic behaviour and stability a commercial aerostatic pad controlled by a custom-built diaphragm valve. The bearing performance is studied by means of a lumped parameters model. Air bearing stiffness and damping are analysed in the frequency domain. Subsequently, the lumped model is linearized to investigate the stability of the system by means of Routh-Hurwitz method. The performance of the controlled air pad is compared to that of a simple commercial air pad.

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