Radial pressure forces in Euler-Euler simulations of turbulent bubbly pipe flows

2021 ◽  
Vol 374 ◽  
pp. 111079
Author(s):  
Roland Rzehak ◽  
Yixiang Liao ◽  
Richard Meller ◽  
Fabian Schlegel ◽  
Ronald Lehnigk ◽  
...  
Keyword(s):  
Radial Pressure ◽  
Pipe Flows

Radial Pressure Wave Behavior in Transient Laminar Pipe Flows Under Different Flow Perturbations

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Tong-Chuan Che ◽  
Huan-Feng Duan ◽  
Pedro J. Lee ◽  
Silvia Meniconi ◽  
Bin Pan ◽  
...  
Keyword(s):  
Radial Pressure ◽  
Research Area ◽  
Laminar Flows ◽  
Generation Mechanism ◽  
Detection Methods ◽  
Pressure Waves ◽  
Pressure Gradients ◽  
Transient Pressure ◽  
Pipe Flows ◽  
2D Model

The study of transient pressure waves in both low- and high-frequency domains has become a new research area to provide potentially high-resolution pipe fault detection methods. In previous research works, radial pressure waves were evidently observed after stopping the laminar pipe flows by valve closures, but the generation mechanism and components of these radial pressure waves are unclear. This paper intends to clarify this phenomenon. To this end, this study first addresses the inefficiencies of the current numerical scheme for the full two-dimensional (full-2D) water hammer model. The modified efficient full-2D model is then implemented into a practical reservoir-pipeline-valve (RPV) system, which is validated by the well-established analytical solutions. The generation mechanism and components of the radial pressure waves, caused by different flow perturbations from valve operations, in transient laminar flows are investigated systematically using this efficient full-2D model. The results indicate that nonuniform changes in the initial velocity profile form pressure gradients along the pipe radius. The existence of these radial pressure gradients is the driving force of the formation of radial flux and radial pressure waves. In addition, high radial modes can be excited, and the frequency of flow perturbations by valve oscillation can redistribute the energy entrapped in each high radial mode.

4.5 CARDIAC OUTPUT ESTIMATION FROM BEAT-TO-BEAT RADIAL PRESSURE AND PULSE WAVE VELOCITY: A MODEL-BASED STUDY

2018 ◽  
Vol 24 (C) ◽  
pp. 76
Author(s):  
Vasiliki Bikia ◽  
Stamatia Pagoulatou ◽  
Theodore G. Papaioannou ◽  
Nikolaos Stergiopulos
Keyword(s):  
Cardiac Output ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Radial Pressure ◽  
Model Based

scholarly journals Perspective on the Response of Turbulent Pipe Flows to Strong Perturbations

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 208
Author(s):  
Liuyang Ding ◽  
Tyler Van Buren ◽  
Ian E. Gunady ◽  
Alexander J. Smits
Keyword(s):  
Pipe Flow ◽  
Abrupt Change ◽  
Pipe Wall ◽  
Surface Condition ◽  
Initial Response ◽  
Body Of Revolution ◽  
Future Directions ◽  
Pipe Flows ◽  
Roughness Elements ◽  
Pipe Geometry

Pipe flow responds to strong perturbations in ways that are fundamentally different from the response exhibited by boundary layers undergoing a similar perturbation, primarily because of the confinement offered by the pipe wall, and the need to satisfy continuity. We review such differences by examining previous literature, with a particular focus on the response of pipe flow to three different kinds of disturbances: the abrupt change in surface condition from rough to smooth, the obstruction due to presence of a single square bar roughness elements of different sizes, and the flow downstream of a streamlined body-of-revolution placed on the centerline of the pipe. In each case, the initial response is strongly influenced by the pipe geometry, but far downstream all three flows display a common feature, which is the very slow, second-order recovery that can be explained using a model based on the Reynolds stress equations. Some future directions for research are also given.

Stability of a Cylinder Under Dynamic Radial Pressure

ARS Journal ◽  
1961 ◽  
Vol 31 (12) ◽  
pp. 1705-1708 ◽  
Author(s):  
JOHN C. YAO
Keyword(s):  
Radial Pressure

Numerical Study of Convective Heat Transfer From Expanding Annular Pipe Flows

2016 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Diameter Ratio ◽  
Wall Heat Transfer ◽  
Reattachment Point ◽  
Transfer Rates ◽  
Pipe Flows ◽  
Annular Pipe

Convective heat transfer from suddenly expanding annular pipe flows are numerically investigated within the steady laminar flow regime. A parametric study is performed to reveal the influence of the annular diameter ratio, k, the Prandtl number, Pr, and the Reynolds number, Re, over the following range of parameters: k = {0, 0.5, 0.7}, Pr = {0.7, 1, 7, 100}, and Re = {25, 50, 100}. Heat transfer enhancement downstream of the expansion plane is only observed for Pr > 1. Peak wall-heat-transfer-rates always appear downstream of the flow reattachment point, in the case of suddenly expanding round pipe flows, i.e. k = 0. However, for suddenly expanding annular pipe flows, i.e., k = 0.5 and 0.7, peak wall-heat-transfer-rates always appear upstream of the flow reattachment point. The observed heat transfer augmentation is more dramatic for suddenly expanding annular flows, in comparison with the one observed for suddenly expanding pipe flows. For a given annular diameter ratio and Reynolds number, increasing the Prandtl number, always results in higher wall-heat-transfer-rates downstream the expansion plane.

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