Thermocapillary Convection of Low Prandtl Number Fluid in a Shallow Cylindrical Pool

In order to understand the characteristics of thermocapillary convection, we conducted a series of unsteady three-dimensional numerical simulations of thermocapillary convection of low Prandtl number fluid in a shallow cylindrical pool with an azimuthal nonuniform temperature, an adiabatic solid bottom and free surface. The simulation results indicate that thermocapillary convection is steady three-dimensional flow at the small Marangoni number. But when Marangoni number exceeds some critical value, the flow will undergo a transition to oscillatory three-dimensional flow. The critical conditions for the onset of oscillatory flow are determined. Details of the flow and temperature fields are discussed, and oscillation frequencies are also exhibited.

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Numerical Simulation of Oscillatory Marangoni Flow in Encapsulated Liquid Bridge

Heat Transfer, Part B ◽

10.1115/imece2005-80795 ◽

2005 ◽

Author(s):

Lan Peng ◽

You-Rong Li ◽

Nobuyuki Imaishi ◽

Dan-Ling Zeng ◽

Qing-Hua Chen

Keyword(s):

Liquid Bridge ◽

Marangoni Number ◽

Oscillatory Flow ◽

Marangoni Convection ◽

Silicone Oil ◽

Temperature Fields ◽

Critical Conditions ◽

Simulation Results ◽

Physical And Mathematical Models ◽

Oscillation Frequencies

The physical and mathematical models of the Marangoni convection of KF-96 silicone oil and FC-70 fluorinart in an encapsulated liquid bridge were established. To contrast to this configuration, the Marangoni convection of KF-96 silicone oil in a liquid bridge was also studied in present work. We conducted a series of unsteady two-dimensional numerical simulations. Simulation conditions correspond to those in the experiments of Majima and Kawamura (2001). The simulation results with large Marangoni number (Ma) predicted oscillatory flows under microgravity. The critical conditions for the onset oscillatory flow were determined and compared with the experimental results. Details of the flow and temperature fields were discussed. Oscillation frequencies were also exhibited.

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3-D Flow Structures Around and Fluid-Dynamic Forces Acting on a Rectangular Cylinder in Oscillatory Flow

Volume 2: Symposia, Parts A, B, and C ◽

10.1115/fedsm2003-45626 ◽

2003 ◽

Author(s):

Takahiro Yasuda ◽

Atsushi Okajima ◽

Minoru Moriyoshi

Keyword(s):

Oscillatory Flow ◽

Three Dimensional ◽

Flow Patterns ◽

Flow Structures ◽

Inertia Force ◽

Water Tank ◽

Height Ratio ◽

Three Dimensional Flow ◽

Dimensional Flow ◽

Rectangular Cylinder

Three-dimensional flow structures around and fluiddynamic forces acting on a rectangular cylinder in oscillatory flow were investigated by numerical simulation using finite volume method. The computations were carried out for three kinds of cross-sections with width/height ratio (d/H) d/H = 0.6, 1.0 and 2.0 and for the amplitude of oscillating flow in the range of 2.5 ≤ the Keulegan-Carpenter number (KC) ≤ 25, the Stokes number (β) = 95. The calculated flow patterns and the drag and inertia force coefficients of Morison equation acting on the cylinder were compared with the experimental ones using a U-tube water tank. In this paper, we note how the KC number and the width/height ratio of the cylinders affect the unsteady and three-dimensional flow structures such as the “longitudinal vortices” and “transverse street” which formed in the case of a circular cylinder fixed in oscillatory flow, and how the CD and the CM values of Morison coefficients change corresponding to the change of the behavior of the flow patterns. Furthermore the relationship between spanwise correlation coefficient of the transverse force R(x3), where x3 is the spanwise position from the bottom of the cylinder, and three-dimensional vortex structures were investigated.

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Three Dimensional Wake Structures of Flow Around an Oscillating Circular Cylinder

Volume 3: Pipeline and Riser Technology; CFD and VIV ◽

10.1115/omae2007-29268 ◽

2007 ◽

Cited By ~ 3

Author(s):

Rafael S. Gioria ◽

Bruno S. Carmo ◽

Julio R. Meneghini

Keyword(s):

Circular Cylinder ◽

Oscillatory Flow ◽

Three Dimensional ◽

Three Dimensional Flow ◽

Dimensional Flow ◽

Shedding Frequency ◽

Vortex Patterns ◽

Lock In ◽

Low Amplitude ◽

Fixed Cylinder

Direct numerical simulationsthe three-dimensional flow around an oscillating circular cylinder are carried out. Imposed body oscillations are realized for low amplitude of oscillation, A/D = 0.4 and for high amplitudes, A/D = 1.0. As the intention is to analyze the amplitude influence in the wake dynamics, the frequency of oscillation is fixed and chosen to be inside the lock-in region, 0.95fs, where fs is the shedding frequency of fixed cylinder. The three-dimensional wake characteristics of the oscillatory body simulations are compared to the fixed body. Floquet stability analysis of two-dimensional oscillatory flow is carried out to complete the investigation and consistently analyze the three-dimensional flow results. The different unstable modes are identified for each of the cases, and they are found to depend basically on the vortex patterns.

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