A numerical solution of unsteady flow problems

Benson, R. S.; Garg, Rajul; Woollatt, D.

doi:10.1016/0020-7403(64)90009-8

Cited by 179 publications

(33 citation statements)

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“…A principal component of this computational method is the discretization of the continuity equation using the approach described by Crowley [17]. When applied to equation (1), this approach is second order accurate in both time and space. If the convection velocity (c 0 in equation (1)) is not constant, however, the accuracy of the numerical scheme is reduced.…”

Section: Methodsmentioning

confidence: 99%

“…It is generally recognized that when used appropriately, these methods are capable of predicting cycleaveraged engine performance parameters with good accuracy [1][2][3][4][5]. When used to predict radiated sound levels, however, these techniques have been somewhat less successful.…”

Section: Introductionmentioning

confidence: 99%

“…These computational techniques have been extensively used in the automotive industry to predict the influence of intake and exhaust system geometry on engine performance parameters such as power output and volumetric efficiency [1][2][3][4][5]. As expected, the non-linear techniques can also be used to predict the acoustic characteristics and radiated sound for the intake and exhaust systems.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Numerical Dissipation and Dispersion on Acoustic Predictions From a Time-Domain Finite Difference Technique for Non-Linear Wave Dynamics

Dickey¹,

Selamet²,

Tallio

2003

Journal of Sound and Vibration

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Numerical Dissipation and Dispersion on Acoustic Predictions From a Time-Domain Finite Difference Technique for Non-Linear Wave Dynamics

Dickey¹,

Selamet²,

Tallio

2003

Journal of Sound and Vibration

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“…Although the principle is simple, as aforementioned, fine tuning the intake or exhaust piping systems is possible only by using the numerical techniques of a nonlinear acoustic theory such as the shock tube theory. The method of characteristics (Benson et al, 1964) and the finite difference method (Ospring et al, 1976) have been used in such a scenario. The important parameters are the magnitude and phase of the instantaneously varying pressures.…”

Section: Introductionmentioning

confidence: 99%

Optimal design of the exhaust system layout to suppress the discharge noise from an idling engine

Choi

Kim

et al. 2011

Int.J Automot. Technol.

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At the idle engine speed, the exhaust discharge noise is influenced by resonances in the whole system, which is composed of connecting pipes and silencers. This pipe resonance radiates a high level of low frequency discharge noise, which is dominated by the low order harmonics of the engine firing frequency. This low frequency noise deteriorates the vehicle's interior noise level and quality. The following study attempted to optimize the layout of an exhaust system to minimize low frequency noise by changing the position of silencers and the lengths of inlet and outlet pipes in each silencer. After modeling the exhaust system using four-pole parameters, the acoustical performance of the system was evaluated using the system insertion loss. In the optimization, the virtual attenuation coefficient, which corresponds to the amount of attenuation coefficient required for the silencers, was calculated to find a minimum value for the layout. The simulated annealing method, which is also known as finding an optimal, was employed in searching for the optimized exhaust layout. Test examples of two cases, for two and six design variables, were used. When the number of design variables was two, the positions of the center and rear silencers were considered. When the number of design variables was six, the positions of the two silencers and the lengths of the inlet and outlet pipes were considered. Three typical layouts for the exhaust system of each case were designed, including the given system and an optimal system. By comparing the predicted and measured discharge noise level, it was confirmed that the optimized exhaust layout has a higher noise reduction than the other layout designs.

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“…To solve such equations (hyperbolic partial differential equations) the method of characteristics can be used. The detailed procedure for the application of this method to reciprocating engines is well documented by Benson [25,26]. On the basis of the equations and the results published by Benson [25,26], we propose in this paper a new implementation of the method of characteristics by using the ACSL software [27][28][29][30][31][32] .…”

Section: Introductionmentioning

confidence: 99%

An Implementation of the Method of Characteristics Using ACSL Software

Hétet

Mezencev

1997

SIMULATION

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The simulation of gas flows in a reciprocating engine requires solution of the equations of gas dynamics because of the pressure waves in the manifolds, for example. The method of characteristics provides a means for solving hyperbolic partial differential equations. We propose in this paper a new way to implement this using ACSL software. After presenting an outline of the method of characteristics and ACSL software, we present a program to solve a simple case: a pressurized pipe with a gradually opening valve. The state event mechanism allows the boundary conditions and the intersections of the characteristics emitted from both ends of the pipe to be dealt with precisely while the solution of the differential equations is realized in a continuous fashion.

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A numerical solution of unsteady flow problems

Cited by 179 publications

References 0 publications

Effects of Numerical Dissipation and Dispersion on Acoustic Predictions From a Time-Domain Finite Difference Technique for Non-Linear Wave Dynamics

Effects of Numerical Dissipation and Dispersion on Acoustic Predictions From a Time-Domain Finite Difference Technique for Non-Linear Wave Dynamics

Optimal design of the exhaust system layout to suppress the discharge noise from an idling engine

An Implementation of the Method of Characteristics Using ACSL Software

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