Linear and Nonlinear Flow Analysis of Elements of a Supersonic Inlet

AIAA Journal ◽  
2021 ◽  
pp. 1-18
Author(s):  
Nikhil Khobragade ◽  
S. Unnikrishnan ◽  
Rajan Kumar
Keyword(s):  
Flow Analysis ◽  
Nonlinear Flow ◽  
Supersonic Inlet ◽  
Linear And Nonlinear

scholarly journals Flow Characteristics through Saturated Soil: Experimental Study

2020 ◽  
Vol 16 ◽  
Keyword(s):  
Critical Analysis ◽  
Soft Soil ◽  
Flow Characteristics ◽  
Saturated Soil ◽  
Nonlinear Flow ◽  
Critical Flow ◽  
Test Results ◽  
Critical Flow Velocity ◽  
Linear And Nonlinear ◽  
Fluid Characteristics

The flow characteristics through saturated soil is complex. For low heads, the flow is essentially linear, where Darcy’s law is applicable. For higher head, the flow is nonlinear and mathematically identified as Forchheimer’s flow. The critical flow velocity for this transition and the relevant Reynold’s number depends upon several factors, including soil and fluid characteristics. In this paper, an experimental investigation has been carried out by means of falling head permeameter with locally available soft soil sample. A critical analysis and interpretations of the test results to identify the linear and nonlinear flow characteristics have been performed and important conclusions are drawn therefrom.

scholarly journals Thermoacoustic instability – a dynamical system and time domain analysis

2014 ◽  
Vol 753 ◽  
pp. 448-471 ◽  
Author(s):  
Taraneh Sayadi ◽  
Vincent Le Chenadec ◽  
Peter J. Schmid ◽  
Franck Richecoeur ◽  
Marc Massot
Keyword(s):  
Time Series ◽  
Heat Source ◽  
Limit Cycle ◽  
Nonlinear Regime ◽  
Galerkin Projection ◽  
Nonlinear Flow ◽  
Mean Flow ◽  
Retarded Time ◽  
Thermoacoustic Instability ◽  
Linear And Nonlinear

AbstractThis study focuses on the Rijke tube problem, which includes features relevant to the modelling of thermoacoustic coupling in reactive flows: a compact acoustic source, an empirical model for the heat source and nonlinearities. This thermoacoustic system features both linear and nonlinear flow regimes with complex dynamical behaviour. In order to synthesize accurate time series, we tackle this problem from a numerical point of view, and start by proposing a dedicated solver designed for dealing with the underlying stiffness – in particular, the retarded time and the discontinuity at the location of the heat source. Stability analysis is performed on the limit of low-amplitude disturbances by using the projection method proposed by Jarlebring (PhD thesis, Technische Universität Braunschweig, 2008), which alleviates the problems arising from linearization with respect to the retarded time. The results are then compared with the analytical solution of the undamped system and with the results obtained from Galerkin projection methods commonly used in this setting. This analysis provides insight into the consequences of the various assumptions and simplifications that justify the use of Galerkin expansions based on the eigenmodes of the unheated resonator. We demonstrate that due to the presence of a discontinuity in the spatial domain, the eigenmodes in the heated case predicted by using Galerkin expansion show spurious oscillations resulting from the Gibbs phenomenon. Finally, time series in the fully nonlinear regime, where a limit cycle is established, are analysed and dominant modes are extracted. By comparing the modes of the linear regime to those of the nonlinear regime, we are able to illustrate the mean-flow modulation and frequency switching, which appear as the nonlinearities become significant and ultimately affect the form of the limit cycle. Analysis of the saturated limit cycles shows the presence of higher-frequency modes, which are linearly stable but become significant through nonlinear growth of the signal. This bimodal effect is not exhibited when the coupling between different frequencies is not accounted for. In conclusion, a dedicated solver for capturing thermoacoustic instability is proposed and methods for analysing linear and nonlinear regions of the resulting time series are introduced.

scholarly journals Unsteady three dimensional flow of couple stress fluid over a stretching surface with chemical reaction

2012 ◽  
Vol 17 (1) ◽  
pp. 47-59 ◽  
Author(s):  
Tasawar Hayat ◽  
Muhammad Awais ◽  
Ambreen Safdar ◽  
Awatif A. Hendi
Keyword(s):  
Chemical Reaction ◽  
Couple Stress ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Nonlinear Flow ◽  
Couple Stress Fluid ◽  
Stretching Surface ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Parameters Of Interest

The unsteady three-dimensional flow of couple stress fluid over a stretched surface is investigated. Analysis has been performed in the presence of mass transfer and chemical reaction. Nonlinear flow analysis is computed by a homotopic approach. Plots are presented and analyzed for the various parameters of interest. A comparative study with existing solutions in a limiting sense is made.

Production flow analysis

1963 ◽  
Vol 42 (12) ◽  
pp. 742 ◽  
Author(s):  
John L. Burbidge
Keyword(s):  
Flow Analysis ◽  
Production Flow

Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

2020 ◽  
pp. 139-143
Keyword(s):  
Absorption Coefficient ◽  
Water Solution ◽  
Optical Limiting ◽  
Refraction Index ◽  
Laser Wavelength ◽  
Solid State Laser ◽  
Natural Dyes ◽  
Linear And Nonlinear ◽  
532 Nm ◽  
Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

Sign in / Sign up

Export Citation Format

Share Document