scholarly journals Degeneracy of turbulent states in two-dimensional channel flow

2021 ◽  
Vol 917 ◽  
Author(s):  
Vilda K. Markeviciute ◽  
Rich R. Kerswell
Keyword(s):  
Channel Flow ◽  
Two Dimensional

Abstract

scholarly journals Streaky structure in a two-dimensional turbulent channel flow.

1985 ◽  
Vol 51 (470) ◽  
pp. 3092-3101 ◽  
Author(s):  
Yoichiro IRITANI ◽  
Nobuhide KASAGI ◽  
Masaru HIRATA
Keyword(s):  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Two Dimensional ◽  
Streaky Structure

scholarly journals The effects of electrostatic forces on the distribution of drops in a channel flow: Two-dimensional oblate drops

2005 ◽  
Vol 17 (9) ◽  
pp. 093302 ◽  
Author(s):  
Arturo Fernández ◽  
Gretar Tryggvason ◽  
Judy Che ◽  
Steven L. Ceccio
Keyword(s):  
Channel Flow ◽  
Two Dimensional ◽  
Electrostatic Forces

Numerical Investigation of Heat Transfer in the Wake of a Single Highly Confined Bubble in a Horizontal Minichannel

2018 ◽  
Author(s):  
John R. Willard ◽  
D. Keith Hollingsworth
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Numerical Investigation ◽  
Channel Flow ◽  
Heat Generation ◽  
Reduced Order Model ◽  
Two Dimensional ◽  
Transfer Enhancement ◽  
Order Model ◽  
Reduced Order

Confined bubbly flows in millimeter-scale channels produce significant heat transfer enhancement when compared to single-phase flows. Experimental studies support the hypothesis that the enhancement is driven by a convective phenomenon in the liquid phase as opposed to sourcing from microlayer evaporation or active nucleation. A numerical investigation of flow structure and heat transfer produced by a single bubble moving through a millimeter-scale channel was performed in order to document the details of this convective mechanism. The simulation includes thermal boundary conditions emulating those of the experiments, and phase change was omitted in order to focus only on the convective mechanism. The channel is horizontal with a uniform-heat-generation upper wall and an adiabatic lower surface. A Lagrangian framework was adopted such that the computational domain surrounds the bubble and moves at the nominal bubble speed. The liquid around the bubble moves as a low-Reynolds-number unsteady laminar flow. The volume-of-fluid method was used to track the liquid/gas interface. This paper reviews the central results of this simulation regarding wake heat transfer. It then compares the findings regarding Nusselt number enhancement to a reduced-order model on a two-dimensional domain in the wake of the bubble. The model solves the advective-diffusion equation assuming a velocity field consistent with fully developed channel flow in the absence of the bubble. The response of the uniform-heat-generation upper wall is included. The model assumes a temperature profile directly behind the bubble which represents a well-mixed region produced by the passage of the bubble. The significant wake heat transfer enhancement and its decay with distance from the bubble documented by the simulation were captured by the reduced-order model. However, the channel surface temperature recovered in a much shorter distance in the simulation compared to the reduced-order model. This difference is attributed to the omission of transverse conduction within the heated surface in the two-dimensional model. Beyond approximately one bubble diameter into the bubble wake, the complex flow structures are replaced by the momentum field of the precursor channel flow. However, the properties and thickness of the heated upper channel wall govern the heat transfer for many bubble diameters behind the bubble.

Lateral Migration of Large and Small Droplets Suspended in Channel Flow

2013 ◽  
Author(s):  
Masato Makino ◽  
Masako Sugihara-Seki
Keyword(s):  
Numerical Simulation ◽  
Channel Flow ◽  
Poiseuille Flow ◽  
Size Difference ◽  
Two Dimensional ◽  
Lateral Migration ◽  
Plane Poiseuille Flow ◽  
Surface Tensions ◽  
Segregation Behavior ◽  
The Mean

In order to investigate the effect of the size differences between suspended particles on the segregation behavior in channel flow of multicomponent suspensions, we conduct a two-dimensional numerical simulation for suspensions of fluid droplets of two different sizes subjected to a plane Poiseuille flow. The large and small droplets are assumed to have equal surface tensions and equal internal viscosities. The temporal evolutions of the lateral positions of the large and small droplets relative to the channel centerline are computed for various size ratios and area ratios of the large and small droplets. It is found that the small droplets tend to migrate toward the channel walls with increasing fraction of the large droplets and that the mean lateral positions of the large droplets are always closer to the channel centerline compared to the mean lateral positions of the small droplets, which represent the margination of the small droplets and the segregation of the droplets caused by the size difference. These trends are enhanced as the size ratio of large and small droplets is increased.

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