Time-dependent near field muzzle brake flow simulations

1982 ◽  
Author(s):  
G. WIDHOPF ◽  
J. BUELL ◽  
E. SCHMIDT
Keyword(s):  
Near Field ◽  
Time Dependent ◽  
Flow Simulations

Compressible Flow Simulations on a Massively Parallel Computer

1991 ◽  
Vol 02 (01) ◽  
pp. 430-436
Author(s):  
ELAINE S. ORAN ◽  
JAY P. BORIS
Keyword(s):  
Compressible Flow ◽  
Chemical Reactions ◽  
Large Scale ◽  
Model Development ◽  
Time Dependent ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Parallel Solution ◽  
Flow Simulations ◽  
Connection Machine

This paper describes model development and computations of multidimensional, highly compressible, time-dependent reacting on a Connection Machine (CM). We briefly discuss computational timings compared to a Cray YMP speed, optimal use of the hardware and software available, treatment of boundary conditions, and parallel solution of terms representing chemical reactions. In addition, we show the practical use of the system for large-scale reacting and nonreacting flows.

scholarly journals Calculations of near-field emissions in frequency-domain into time-dependent data with arbitrary wave form transient perturbations

2012 ◽  
Vol 1 (2) ◽  
pp. 26
Author(s):  
Y. Liu ◽  
B. Ravelo ◽  
J. Ben Hadj Slama
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Wave Spectrum ◽  
Computational Method ◽  
Time Dependent ◽  
Dependent Data ◽  
Wave Form ◽  
Frequency Dependent ◽  
Transient Electromagnetic ◽  
The Time Domain

This paper is devoted on the application of the computational method for calculating the transient electromagnetic (EM) near-field (NF) radiated by electronic structures from the frequency-dependent data for the arbitrary wave form perturbations i(t). The method proposed is based on the fast Fourier transform (FFT). The different steps illustrating the principle of the method is described. It is composed of three successive steps: the synchronization of the input excitation spectrum I(f) and the given frequency data H0(f), the convolution of the two inputs data and then, the determination of the time-domain emissions H(t). The feasibility of the method is verified with standard EM 3D simulations. In addition to this method, an extraction technique of the time-dependent z-transversal EM NF component Xz(t) from the frequency-dependent x- and y- longitudinal components Hx(f) and Hy(f) is also presented. This technique is based on the conjugation of the plane wave spectrum (PWS) transform and FFT. The feasibility of the method is verified with a set of dipole radiations. The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs).

The use of Gaussian trend surfaces for modelling glacio-isostatic crustal rebound

2004 ◽  
Vol 40 (2) ◽  
pp. 175-179 ◽  
Author(s):  
P. Fretwell ◽  
I. R. Peterson ◽  
D. E. Smith
Keyword(s):  
Empirical Data ◽  
Near Field ◽  
Gaussian Function ◽  
Sea Surface ◽  
Time Dependent ◽  
Far Field ◽  
Trend Surface ◽  
Surface Level ◽  
Mathematical Solution ◽  
Better Than

SynopsisThe behaviour of the Earth's continental crust and mantle may be modelled as a buoyant floating plate on a viscous liquid, and the variations of load imposed by an ice sheet may be modelled as a time-dependent force. In recent work it has been shown that the mathematical solution of this problem can be subdivided into a propagating far-field forebulge term and a non-propagating near-field term. The latter often dominates and can be approximated satisfactorily by a generalized Gaussian function. Here we fit empirical data from the Main Postglacial Shoreline of northern Britain to a Gaussian trend surface. We show that the fit is significantly better than that of a polynomial trend surface previously published, and that the method has the potential to predict the likely sea surface level offshore at the zero isobase for the shoreline.

scholarly journals The effect of tethering on the clearance rate of suspension-feeding plankton

2020 ◽  
Vol 117 (48) ◽  
pp. 30101-30103
Author(s):  
Anders Andersen ◽  
Thomas Kiørboe
Keyword(s):  
Clearance Rate ◽  
Flow Model ◽  
Near Field ◽  
Suspension Feeding ◽  
Suspension Feeders ◽  
Flow Simulations ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Feeding Modes ◽  
Number Flow

Many planktonic suspension feeders are attached to particles or tethered by gravity when feeding. It is commonly accepted that the feeding flows of tethered suspension feeders are stronger than those of their freely swimming counterparts. However, recent flow simulations indicate the opposite, and the cause of the opposing conclusions is not clear. To explore the effect of tethering on suspension feeding, we use a low-Reynolds-number flow model. We find that it is favorable to be freely swimming instead of tethered since the resulting feeding flow past the cell body is stronger, leading to a higher clearance rate. Our result underscores the significance of the near-field flow in shaping planktonic feeding modes, and it suggests that organisms tether for reasons that are not directly fluid dynamical (e.g., to stay near surfaces where the concentration of bacterial prey is high).

Transient Blade Load Determination in behind Ship Condition based on CFD

2015 ◽  
Author(s):  
Norbert Bulten
Keyword(s):  
Fatigue Strength ◽  
Velocity Field ◽  
Time Dependent ◽  
Propeller Blade ◽  
Inflow Velocity ◽  
Flow Simulations ◽  
Load Fluctuation ◽  
Propeller Performance ◽  
The Impact

With the aid of detailed numerical flow simulations it has become possible to determine the isolated propeller blade load during a revolution. The load fluctuation on a single propeller blade can be clearly related to the inflow velocity field. Once the time dependent load, and consequently the performance, of a single blade has been identified, knowledge can be obtained on possible overall improvement of the propeller performance. Also the impact on fatigue strength can be addressed in more detail. In this paper the propeller blade load fluctuations have been analyzed for a propeller in behind ship and in a tunnel, operating as bow thruster. The impact of the inflow to the propeller on the occurring loads will be shown. In case of tunnel thruster units, also possible actions to improve the inflow will be analyzed.

scholarly journals Time-dependent prediction of the unsteady pressure near-field from an under-expanded jet

2014 ◽  
Author(s):  
Aldo Rona ◽  
Danilo Di Stefano ◽  
Alessandro Mancini ◽  
Edward Hall
Keyword(s):  
Near Field ◽  
Time Dependent ◽  
Unsteady Pressure
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