Oscillations in the near field of a heated two-dimensional jet

Yu, Ming-Huei; Monkewitz, Peter A.

doi:10.1017/s0022112093002502

Cited by 53 publications

(37 citation statements)

References 22 publications

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“…The global analysis based on linear absolute instability concepts successfully predicts the occurrence of finite amplitude Global modes in counter-flow mixing layers (Strykowski & Niccum 1991, Strykowski et al 1996, wakes with or without suction (Hammond & Redekopp 1997, Leu & Ho 2000, Oertel 1990, Woodley & Peake 1997, hot or helium jets (Kyle & Sreenivasan 1993, Sreenivasan et al 1989, Yu & Monkewitz 1993, separated boundary layer flows over a double-bump topography (Marquillie & Ehrenstein 2003; see Figure 1), or even flickering candles (Maxworthy 1999), among many other examples.…”

Section: Global Linear Stability Analysis Of Weakly Nonparallel Flowsmentioning

confidence: 96%

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

Chomaz

2005

Annu. Rev. Fluid Mech.

606

565

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Key Words absolute/convective instabilities, transient growth, fronts, Global modes, passive and active control ■ Abstract The objective of this review is to critically assess the different approaches developed in recent years to understand the dynamics of open flows such as mixing layers, jets, wakes, separation bubbles, boundary layers, and so on. These complex flows develop in extended domains in which fluid particles are continuously advected downstream. They behave either as noise amplifiers or as oscillators, both of which exhibit strong nonlinearities (Huerre & Monkewitz 1990). The local approach is inherently weakly nonparallel and it assumes that the basic flow varies on a long length scale compared to the wavelength of the instability waves. The dynamics of the flow is then considered as a superposition of linear or nonlinear instability waves that, at leading order, behave at each streamwise station as if the flow were homogeneous in the streamwise direction. In the fully global context, the basic flow and the instabilities do not have to be characterized by widely separated length scales, and the dynamics is then viewed as the result of the interactions between Global modes living in the entire physical domain with the streamwise direction as an eigendirection. This second approach is more and more resorted to as a result of increased computational capability. The earlier review of Huerre & Monkewitz (1990) emphasized how local linear theory can account for the noise amplifier behavior as well as for the onset of a Global mode. The present survey first adopts the opposite point of view by demonstrating how fully global theory accounts for the noise amplifier behavior of open flows. From such a perspective, there is strong emphasis on the very peculiar nonorthogonality of linear Global modes, which in turn allows a novel interpretation of recent numerical simulations and experimental observations. The nonorthogonality of linear Global modes also imposes severe constraints on the extension of linear global theory to the fully nonlinear régime. When the flow is weakly nonparallel, this limitation is so severe that the linear Global mode theory is of little help. It is then much more appropriate to develop a fully nonlinear formulation involving the presence of a front separating the base state region from the bifurcated state region.

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Section: Global Linear Stability Analysis Of Weakly Nonparallel Flowsmentioning

confidence: 96%

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

Chomaz

2005

Annu. Rev. Fluid Mech.

606

565

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“…We consider symmetric solutions (seen in experiments [20]) of the plane jet ow which are determined by the velocity and density proÿles at the in ow plane. The streamwise velocity component and density were u(x = 0; y) = 1 2 1 + tanh 2…”

Section: Unstable Variable-density Plane Jetmentioning

confidence: 99%

A high‐resolution scheme for low Mach number flows

Chakravorty

Mathew

2004

Numerical Methods in Fluids

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SUMMARYA method for computing low Mach number ows using high-resolution interpolation and di erence formulas, within the framework of the Marker and Cell (MAC) scheme, is presented. This increases the range of wavenumbers that are properly resolved on a given grid so that a su ciently accurate solution can be obtained without extensive grid reÿnement. Results using this scheme are presented for three problems. The ÿrst is the two-dimensional Taylor-Green ow which has a closed form solution. The second is the evolution of perturbations to constant-density, plane channel ow for which linear stability solutions are known. The third is the oscillatory instability of a variable density plane jet. In this case, unless the sharp density gradients are resolved, the calculations would breakdown. Underresolved calculations gave solutions containing vortices which grew in place rather than being convected out. With the present scheme, regular oscillations of this instability were obtained and vortices were convected out regularly. Stable computations were possible over a wider range of sensitive parameters such as density ratio and co-ow velocity ratio.

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“…Instead, the frequency is determined by the jet dimension and the density gradient. It is an intrinsic characteristic of a low density jet, similar to the Karman vortex street in a flow passing over a cylinder [12,13].…”

Section: Introductionmentioning

confidence: 99%

A numerical study of fluid injection and mixing under near-critical conditions

Yang

2012

Acta Mech Sin

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Nitrogen injection under conditions close vicinity of the liquid-gas critical point is studied numerically. The fluid thermodynamic and transport properties vary drastically and exhibit anomalies in the near-critical regime. These anomalies can cause distinctive effects on heat-transfer and fluid-flow characteristics. To focus on the influence of thermodynamics on the flow field, a relatively low injection Reynolds number of 1 750 is adopted. For comparisons, a reference case with the same configuration and Reynolds number is simulated in the ideal gas regime. The model accommodates full conservation laws, real-fluid thermodynamic and transport phenomena. Results reveal that the flow features of the near-critical fluid jet are significantly different from their counterpart. The near-critical fluid jet spreads faster and mixes more efficiently with the ambient fluid along with a more rapidly development of the vortex pairing process. Detailed analysis at different streamwise locations including both the flat shear-layer region and fully developed vortex region reveals the important effect of volume dilatation and baroclinic torque in the near-critical fluid case. The former disturbs the shear layer and makes it more unstable. The volume dilatation and baroclinic effects strengthen the vorticity and stimulate the vortex rolling up and pairing process.

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Oscillations in the near field of a heated two-dimensional jet

Cited by 53 publications

References 22 publications

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

A high‐resolution scheme for low Mach number flows

A numerical study of fluid injection and mixing under near-critical conditions

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