scholarly journals On an evolutionary nonlinear fluid model in the limiting case

2001 ◽  
Vol 126 (2) ◽  
pp. 421-428
Author(s):  
Stephan Luckhaus ◽  
Josef Málek
Keyword(s):  
Fluid Model ◽  
Limiting Case ◽  
Nonlinear Fluid

scholarly journals On the flow of MHD generalized maxwell fluid via porous rectangular duct

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 989-1002
Author(s):  
Aamir Farooq ◽  
Muhammad Kamran ◽  
Yasir Bashir ◽  
Hijaz Ahmad ◽  
Azeem Shahzad ◽  
...  
Keyword(s):  
Fluid Model ◽  
Maxwell Fluid ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Rectangular Duct ◽  
Modified Darcy’S Law ◽  
Initial Boundary Value ◽  
Generalized Maxwell Fluid ◽  
Limiting Case ◽  
The Impact

Abstract The purpose of this proposed investigation is to study unsteady magneto hydrodynamic (MHD) mixed initial-boundary value problem for incompressible fractional Maxwell fluid model via oscillatory porous rectangular duct. Considering the modified Darcy’s law, the problem is simplified by using the method of the double finite Fourier sine and Laplace transforms. As a limiting case of the general solutions, the same results can be obtained for the classical Maxwell fluid. Also, the impact of magnetic parameter, porosity of medium, and the impact of various material parameters on the velocity profile and the corresponding tangential tensions are illuminated graphically. At the end, we will give the conclusion of the whole paper.

Improved nonlinear fluid model in rotating flow

2012 ◽  
Vol 33 (11) ◽  
pp. 1419-1430 ◽  
Author(s):  
N. Ashrafi ◽  
H. Karimi-Haghighi
Keyword(s):  
Fluid Model ◽  
Rotating Flow ◽  
Nonlinear Fluid

Nonlinear excitation of vortices at the upper-hybrid layer

1981 ◽  
Vol 25 (3) ◽  
pp. 509-514 ◽  
Author(s):  
H. U. Rahman ◽  
M. Y. Yu ◽  
P. K. Shukla
Keyword(s):  
Fluid Model ◽  
Modulational Instability ◽  
Hybrid Layer ◽  
Confined Plasmas ◽  
Magnetically Confined ◽  
Two Fluid Model ◽  
Convective Cells ◽  
Hybrid Waves ◽  
Limiting Case ◽  
Magnetically Confined Plasmas

It is shown that convective cells can be excited by large-amplitude propagating upper-hybrid waves in a plasma. Using the two-fluid model, we obtain a coupled set of differential equations. A nonlinear dispersion relation for the modulational instability is then derived. This relation is investigated for two parameter regimes and expressions for the growth rates are obtained analytically. The limiting case of a dipole pump field is also considered. The relevance of our work in laser-produced, as well as magnetically confined, plasmas is discussed.

Minimal Order Nonlinear Observer for Leak Detection

2004 ◽  
Vol 126 (3) ◽  
pp. 467-472 ◽  
Author(s):  
C. Verde
Keyword(s):  
Fluid Model ◽  
Practical Method ◽  
Nonlinear Observer ◽  
Minimal Order ◽  
Nonlinear Observers ◽  
Proposed Model ◽  
Robust Filters ◽  
Output Component ◽  
Nonlinear Fluid ◽  
Nonlinear Robust

A method for leaks location in a pipeline, using sensors only at the extremes of the line is presented. The detection problem is solved, assuming a nonlinear fluid model of finite dimension with uncertainty in the leak position, and generating the residual with two minimal order nonlinear observers. Flow and pressure data at the beginning and at end of the line are considered as output and input of the system respectively. Since the proposed model satisfies (1) the condition to generate a residual, assuming at the most two leaks, and (2) the strong detectability fault property for each output component, two nonlinear robust filters with respect to a leak are designed to generate the residual. To simplify the residual evaluation and estimate the leak position, a static relationship between each component of the residual and the position error is derived. The main contribution of this paper is to take advantage of the residual equation with uncertainty to isolate a fault. The effectiveness of this approach is shown by a comparison with the practical method reported in [1] using results obtained from simulated and experimental data of a water pilot pipeline of 132 m long, with a diameter of 0.1 m and with a flow rate of 12 l/s.

Statistical Response of a Simplified Nonlinear Fluid Model Under Random Parameters

2007 ◽  
Author(s):  
T-P. Chang
Keyword(s):  
Fluid Model ◽  
Closed Form Solution ◽  
Mean Value ◽  
Form Solution ◽  
Viscoelastic Materials ◽  
Nonlinear Springs ◽  
Constant Rate ◽  
Viscoelastic Modeling ◽  
Spring Constants ◽  
Nonlinear Fluid

In this paper, a simplified spring-dashpot model is proposed to represent the complicated nonlinear response of some viscoelastic materials. Recently, the viscoelastic modeling has been adopted by many researchers to characterize some parts of human body in bioengineering. Among others, the following researchers have already contributed to the development of this field (Weiss et al., [1]; Guedes et al., [2]). Sometimes it is impossible to estimate the constant parameters in the model deterministically, therefore, the damping coefficient of the dashpot and the spring constants of the linear and nonlinear springs are considered as stochastic to characterize the random properties of the viscoelastic materials. The mean value of the displacement of the nonlinear model, subjected to constant rate displacement, can be solved analytically. Based on the closed-form solution, the proposed method produces the statistical responses of the simplified nonlinear fluid model, which is fairly useful in estimating the reliability of the nonlinear system.

Stochastic Dynamic Response of a Simplified Nonlinear Fluid Model for Viscoelastic Materials

2012 ◽  
Vol 28 (2) ◽  
pp. 365-372 ◽  
Author(s):  
T.-P. Chang
Keyword(s):  
Dynamic Response ◽  
Closed Form ◽  
Fluid Model ◽  
Closed Form Solution ◽  
Mean Value ◽  
Form Solution ◽  
Stochastic Dynamic ◽  
Viscoelastic Materials ◽  
Viscoelastic Modeling ◽  
Nonlinear Fluid

AbstractIn the present study, we propose a simplified nonlinear fluid model to characterize the complex nonlinear response of some viscoelastic materials. Recently, the viscoelastic modeling has been utilized by many researchers to simulate some parts of human body in bioengineering and to represent many material properties in mechanical engineering, electronic engineering and construction engineering. Occasionally it is almost impossible to evaluate the constant parameters in the model in the deterministic sense, therefore, the damping coefficient of the dashpot and the spring constants of the linear and nonlinear springs are considered as stochastic to model the stochastic properties of the viscoelastic materials. After some transformations, the closed-form solution can be obtained for the mean value of the displacement of the simplified nonlinear fluid model, subjected to constant rate of displacement. Based on the closed-form solution, the proposed method generates the stochastic dynamic response of the simplified nonlinear model, which plays an important role in performing the reliability analysis of the nonlinear system.

Fluid Model Driven by an Ornstein-Uhlenbeck Process

1994 ◽  
Vol 8 (3) ◽  
pp. 403-417 ◽  
Author(s):  
Vidyadhar Kulkarni ◽  
Tomasz Rolski
Keyword(s):  
Fluid Model ◽  
Heavy Traffic ◽  
Change Of Measure ◽  
Tail Probabilities ◽  
Uhlenbeck Process ◽  
Model Driven ◽  
Ornstein Uhlenbeck Process ◽  
Exponential Bounds ◽  
Limiting Case ◽  
Measure Technique

In this paper we consider a fluid model of a single buffer in a random external environment modeled by an Ornstein-Uhlenbeck process. Such a model appears as the limiting case of the multiplexing model of Anick, Mitra, and Sondhi [2] in a heavy traffic environment. We use the change of measure technique to derive an exponential upper bound on the tail probabilities of the steady-state buffer content. We also establish an asymptotic upper and lower exponential bounds on the tail probabilities.

A nonlinear fluid model for pulmonary blood circulation

1993 ◽  
Vol 26 (6) ◽  
pp. 653-664 ◽  
Author(s):  
C.W. Li ◽  
H.D. Cheng
Keyword(s):  
Blood Circulation ◽  
Fluid Model ◽  
Nonlinear Fluid

scholarly journals Nonlinear Fluid Models for Biofluid Flow in Constricted Blood Vessels under Body Accelerations: A Comparative Study

2012 ◽  
Vol 2012 ◽  
pp. 1-27
Author(s):  
D. S. Sankar ◽  
Atulya K. Nagar
Keyword(s):  
Flow Rate ◽  
Fluid Model ◽  
Plug Flow ◽  
Casson Fluid ◽  
Fluid Models ◽  
Mean Flow ◽  
Mean Velocity ◽  
Casson Fluid Model ◽  
The Mean ◽  
Nonlinear Fluid

Pulsatile flow of blood in constricted narrow arteries under periodic body acceleration is analyzed, modeling blood as non-Newtonian fluid models with yield stress such as (i) Herschel-Bulkley fluid model and (ii) Casson fluid model. The expressions for various flow quantities obtained by Sankar and Ismail (2010) for Herschel-Bulkley fluid model and Nagarani and Sarojamma (2008), in an improved form, for Casson fluid model are used to compute the data for comparing these fluid models. It is found that the plug core radius and wall shear stress are lower for H-B fluid model than those of the Casson fluid model. It is also noted that the plug flow velocity and flow rate are considerably higher for H-B fluid than those of the Casson fluid model. The estimates of the mean velocity and mean flow rate are considerably higher for H-B fluid model than those of the Casson fluid model.

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