scholarly journals Slip Model Performance for Micro-scale Gas Flows

2003 ◽  
Author(s):  
Matthew McNenly ◽  
Michael Gallis ◽  
Iain Boyd
Keyword(s):  
Model Performance ◽  
Gas Flows ◽  
Slip Model ◽  
Micro Scale

Slip-model performance for underexpanded micro-scale rocket nozzle flows

2007 ◽  
Vol 16 (3) ◽  
pp. 223-230 ◽  
Author(s):  
José A. Moríñigo ◽  
José Hermida Quesada ◽  
Francisco Caballero Requena
Keyword(s):  
Model Performance ◽  
Slip Model ◽  
Rocket Nozzle ◽  
Micro Scale ◽  
Nozzle Flows

scholarly journals Validation of a Second-Order Slip Model for Transition-Regime, Gaseous Flows

2004 ◽  
Author(s):  
Nicolas G. Hadjiconstantinou
Keyword(s):  
Second Order ◽  
Stress Fields ◽  
Gas Flows ◽  
Transition Regime ◽  
Slip Model ◽  
Dilute Gas ◽  
Transient Problems ◽  
Model Predictions ◽  
Gaseous Flows ◽  
Related Stress

We discuss and validate a recently proposed second-order slip model for dilute gas flows. Our discussion focuses on the importance of quantitatively accounting for the effect of Knudsen layers close to the walls. This is important, not only for obtaining an accurate slip model but also for interpreting the results of the latter since in transition-regime flows the Knudsen layers penetrate large parts of the flow. Our extensive validation illustrates the above points by comparing direct Monte Carlo solutions to the slip model predictions for an unsteady flow. Excellent agreement is found between simulation and the slip model predictions up to Kn = 0.4, for both the velocity profile and stress at the wall. This demonstrates that the proposed second-order slip model reliably describes arbitrary flowfields (and related stress fields) in a predictive manner at least up to Kn = 0.4 for both steady and transient problems.

scholarly journals A Feasibility Study of Simulating the Micro-Scale Wind Field for Wind Energy Applications by NWP/CFD Model with Improved Coupling Method and Data Assimilation

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2549
Author(s):  
Shaohui Li ◽  
Xuejin Sun ◽  
Riwei Zhang ◽  
Chuanliang Zhang
Keyword(s):  
Data Assimilation ◽  
Wind Energy ◽  
Wind Field ◽  
Weather Prediction ◽  
Model Performance ◽  
Coupling Method ◽  
Cfd Model ◽  
Wind Fields ◽  
Micro Scale ◽  
Cfd Models

Understanding the details of micro-scale wind fields is important in the development of wind energy. Research has proven that coupling Numerical Weather Prediction (NWP) and Computational Fluid Dynamics (CFD) models is a better approach for micro-scale wind field simulation. The main purpose of this work is to improve the NWP/CFD model performance in two parts: (i) developing a new coupling method that is more suitable for complex terrain between the NWP and CFD models, and (ii) applying a data assimilation system in the CFD model. Regarding part (i), in order to solve the problem of great topographical difference at the domain boundaries between the two models, Cressman interpolation is utilized to impose the NWP model wind on the CFD model boundaries. In part (ii), an assimilation method, nudging, to apply assimilation of observations into the CFD model is explored. Based on the Cressman interpolation coupling method, a preliminary implementation of data assimilation is performed. The results show that the NWP/CFD model with the improved coupling method may capture the details of micro-scale wind fields more accurately. Using data assimilation, the NWP/CFD model performance may be further improved by cooperating observation data.

scholarly journals Particle simulation of micro-scale gas flows

2001 ◽  
Author(s):  
Iain Boyd ◽  
Quanhua Sun
Keyword(s):  
Particle Simulation ◽  
Gas Flows ◽  
Micro Scale

scholarly journals Development of an Efficient Particle Approach for Micro-Scale Gas Flow Simulations

2009 ◽  
Author(s):  
Quanhua Sun ◽  
Feng Li ◽  
Jing Fan ◽  
Chunpei Cai
Keyword(s):  
Cell Size ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Gas Flows ◽  
Dsmc Method ◽  
Low Speed ◽  
Micro Scale ◽  
Information Preservation ◽  
Cfd Method

The micro-scale gas flows are usually low-speed flows and exhibit rarefied gas effects. It is challenging to simulate these flows because traditional CFD method is unable to capture the rarefied gas effects and the direct simulation Monte Carlo (DSMC) method is very inefficient for low-speed flows. In this study we combine two techniques to improve the efficiency of the DSMC method. The information preservation technique is used to reduce the statistical noise and the cell-size relaxed technique is employed to increase the effective cell size. The new cell-size relaxed IP method is found capable of simulating micro-scale gas flows as shown by the 2D lid-driven cavity flows.

scholarly journals A slip model for micro/nano gas flows induced by body forces

2009 ◽  
Vol 8 (3) ◽  
pp. 417-422 ◽  
Author(s):  
Q. D. To ◽  
C. Bercegeay ◽  
G. Lauriat ◽  
C. Léonard ◽  
G. Bonnet
Keyword(s):  
Gas Flows ◽  
Slip Model ◽  
Body Forces

Influence of Surface Roughness on Micro-Scale Rarefied Gas Flows

2008 ◽  
Author(s):  
O. A. Aksenova ◽  
L. A. Khalidov ◽  
Takashi Abe
Keyword(s):  
Surface Roughness ◽  
Rarefied Gas ◽  
Gas Flows ◽  
Micro Scale ◽  
Rarefied Gas Flows
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