Stability of wall-bounded shear layers in the 

presence of simulated distributed surface roughness

Floryan, J. M.

doi:10.1017/s0022112096004429

Cited by 83 publications

(68 citation statements)

References 6 publications

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“…The ow has Poiseuille form initially and is disturbed by sudden imposition of suction at the initial time. The initial transient dies out after approximately 200 time units and the solution approaches steady form identical to that obtained by Floryan [18] in a steady state analysis. Additional comparisons are given in Table I.…”

Section: Flow Modiÿcations Induced By Application Of Periodic Suctionsupporting

confidence: 68%

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Finite‐difference 4th‐order compact scheme for the direct numerical simulation of instabilities of shear layers

Jiang

Floryan

2005

Numerical Methods in Fluids

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SUMMARYAn algorithm based on the 4th-order ÿnite-di erence compact scheme is developed and applied in the direct numerical simulations of instabilities of channel ow. The algorithm is illustrated in the context of stream function formulation that leads to ÿeld equation involving 4th-order spatial derivatives. The ÿnite-di erence discretization in the wall-normal direction uses ÿve arbitrarily spaced points. The discretization coe cients are determined numerically, providing a large degree of exibility for grid selection. The Fourier expansions are used in the streamwise direction. A hybrid Runge-Kutta=Crank-Nicholson lowstorage scheme is applied for the time discretization. Accuracy tests demonstrate that the algorithm does deliver the 4th-order accuracy. The algorithm has been used to simulate the natural instability processes in channel ow as well as processes occurring when the ow is spatially modulated using wall transpiration. Extensions to three-dimensional situations are suggested.

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Section: Flow Modiÿcations Induced By Application Of Periodic Suctionsupporting

confidence: 68%

“…Arbitrary suction distribution can be represented in terms of Fourier expansions [18]. In our test we shall consider suction described only by one Fourier mode, i.e.…”

Section: Flow Modiÿcations Induced By Application Of Periodic Suctionmentioning

confidence: 99%

Finite‐difference 4th‐order compact scheme for the direct numerical simulation of instabilities of shear layers

Jiang

Floryan

2005

Numerical Methods in Fluids

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“…(2). This is the same decomposition approach as described by [18] and [19]. The linear analysis by [15] also shows that these linearized equations do demonstrate secondary instabilities induced by the traveling wave.…”

Section: B Moving-frame Decompositionmentioning

confidence: 72%

Controller Synthesis for Periodic, Linear-Distributed Parameter Systems: A Channel Flow Application

Kang

Speyer

Kim

2015

AIAA Guidance, Navigation, and Control Conference

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A framework is presented in which temporally periodic, linear, distributed parameter systems can be converted to a time-invariant system. This conversion is key for the control of the secondary instabilities in three-dimensional channel flow induced by an upstream traveling wave of zero-net mass flux of wall transpiration. Linearized dynamical equations derived from Floquet analysis have shown that the instabilities are a direct result of the primary disturbance of the traveling wave but do not provide an analytical framework upon which to design a feedback controller. The necessary observation, although simple but subtle, is that the dynamics of the steady-state flow induced by a traveling wave must be linearized and decomposed in a frame of reference moving with the traveling wave. The resulting linear time-invariant equations are appropriate for system theoretic feedback control synthesis, i.e., H 2 and H ∞ methods. Although the linearization method produces a time-invariant linear system in the moving frame, the controller is periodic from a fixed reference frame. This approach for constructing a time-invariant system with periodic inputs is applicable to any system in which the dynamics are described as a combination of a static base and a periodic primary disturbance.

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“…Above a critical level, surface roughness has been shown to affect the laminar-turbulent transit transition in a fluid in contact with the surface. [49][50][51] The critical level can be determined by calculating the roughness Reynolds number,…”

Section: Effect Of Surface Roughnessmentioning

confidence: 99%

“…Therefore, the surfaces applied in this study were considered hydraulically smooth, 49 such that the level of roughness would not change the hydrodynamics of the system. A roughness of [2 lm would be necessary to affect the laminar-turbulent transition in the device at these tip speeds.…”

Section: Effect Of Surface Roughnessmentioning

confidence: 99%

Factors influencing antibody stability at solid–liquid interfaces in a high shear environment

Biddlecombe¹,

Smith²,

Uddin³

et al. 2009

Biotechnology Progress

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A rotating disk shear device was used to study the effect of interfacial shear on the structural integrity of human monoclonal antibodies of IgG4 isotype. Factors associated with the solution conditions (pH, ionic strength, surfactant concentration, temperature) and the interface (surface roughness) were studied for their effect on the rate of IgG4 monomer loss under high shear conditions. The structural integrity of the IgG4 was probed after exposure to interfacial shear effects by SDS-PAGE, IEF, dynamic light scattering, and peptide mapping by LC-MS. This analysis revealed that the main denaturation pathway of IgG4 exposed to these effects was the formation of large insoluble aggregates. Soluble aggregation, breakdown in primary structure, and chemical modifications were not detected. The dominant factors found to affect the rate of IgG4 monomer loss under interfacial shear conditions were found to be pH and the nanometer-scale surface roughness associated with the solid-liquid interface. Interestingly, temperature was not found to be a significant factor in the range tested (15-45 degrees C). The addition of surfactant was found to have a significant stabilizing effect at concentrations up to 0.02% (w/v). Implications of these findings for the bioprocessing of this class of therapeutic protein are briefly discussed.

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Stability of wall-bounded shear layers in the presence of simulated distributed surface roughness

Cited by 83 publications

References 6 publications

Finite‐difference 4th‐order compact scheme for the direct numerical simulation of instabilities of shear layers

Finite‐difference 4th‐order compact scheme for the direct numerical simulation of instabilities of shear layers

Controller Synthesis for Periodic, Linear-Distributed Parameter Systems: A Channel Flow Application

Factors influencing antibody stability at solid–liquid interfaces in a high shear environment

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