Source parameters for the numerical simulation of lightning as a nonlinear acoustic source

2014 ◽  
Vol 136 (4) ◽  
pp. 2223-2223
Author(s):  
Andrew Marshall ◽  
Neal Evans ◽  
Chris Hackert ◽  
Karl Oelschlaeger
Keyword(s):  
Numerical Simulation ◽  
Source Parameters ◽  
Acoustic Source ◽  
Nonlinear Acoustic

Nonlinear Influence of Sound on the Vibrational Energy of Molecules in a Relaxing Gas

2012 ◽  
Vol 37 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Anna Perelomova
Keyword(s):  
High Frequency ◽  
Degrees Of Freedom ◽  
Vibrational Energy ◽  
Acoustic Energy ◽  
Acoustic Source ◽  
Weakly Nonlinear ◽  
Dispersive Flow ◽  
Nonlinear Character ◽  
Nonlinear Acoustic ◽  
Relaxing Gas

AbstractDynamics of a weakly nonlinear and weakly dispersive flow of a gas where molecular vibrational relaxation takes place is studied. Variations in the vibrational energy in the field of intense sound is considered. These variations are caused by a nonlinear transfer of the acoustic energy into energy of vibrational degrees of freedom in a relaxing gas. The final dynamic equation which describes this is instantaneous, it includes a quadratic nonlinear acoustic source reflecting the nonlinear character of interaction of high-frequency acoustic and non-acoustic motions in a gas. All types of sound, periodic or aperiodic, may serve as an acoustic source. Some conclusions about temporal behavior of the vibrational mode caused by periodic and aperiodic sounds are made.

scholarly journals STUDY OF ACOUSTIC SOURCE EXCITED BY PULSED MAGNETIC FIELD

2021 ◽  
pp. 2140008
Author(s):  
YANJU YANG ◽  
CHUNLEI CHENG ◽  
WENYAO YANG ◽  
JIE LI ◽  
ZHENGFU CHENG ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Analytical Solution ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Induction ◽  
Pulsed Magnetic Field ◽  
Magnetic Flux Density ◽  
Acoustic Source ◽  
Thermoacoustic Imaging

In magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging, tissues are exposed to an alternating field, generating magnetoacoustic and thermoacoustic effects in the tissues. This study aimed to investigate the relationship between magnetoacoustic and thermoacoustic effects in a low-conductivity object put in a Gauss-pulsed alternating magnetic field. First, the derivations of the magnetic flux density and electric field strength induced by a Gauss-pulsed current flowing through the coil based on the theory of electromagnetic field were examined. Second, the analytical solution of the magnetic field was studied by simulation. To validate the accuracy of the analytical solution, the analytical solution and the numerical simulation of the magnetic flux density were compared. It shows that the analytical solution coincides with the numerical simulation well. Then, based on the theoretical analysis of the acoustic source generation, numerical studies were conducted to simulate pressures excited by magnetoacoustic and thermoacoustic effects in low-conductivity objects similar to tissues in the Gauss-pulsed magnetic field. The thermoacoustic effect played a leading role in low-conductivity objects placed in the Gauss-pulsed magnetic field, and the magnetoacoustic effect could be ignored. This study provided the theoretical basis for further research on magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging for pathological tissues.

The Role of Goldack Double Ellipsoidal Parameters in Temperature Distribution for the GTAW Process

2020 ◽  
Author(s):  
A Karpagaraj ◽  
SURESH KUMAR S ◽  
S Thamizhmanii ◽  
Arun Nelliappan T ◽  
Siva Shanmugam N ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Heat Source ◽  
Source Parameters ◽  
Welding Process ◽  
Source Model ◽  
Depth Of Penetration ◽  
Factorial Method ◽  
Gtaw Process ◽  
Full Factorial

Abstract Numerical simulation is widely used in all the fields of engineering to predict the results. In welding, various finite element tools are used to predict the bead profile, temperature distribution, joint strength, formability and metallurgical changes etc. With respect to the welding process suitable heat source model has to be assigned for numerical simulation. The most suitable heat source for Gas Tungsten Arc Welding (GTAW) process is the Goldack double ellipsoidal model. This model has few parameters like the width of the weld (a), depth of penetration (b), front profile ellipse (Cf) and rear ellipse profile (Cr). In this research article, the influence of these parameters and their effect on the temperature distribution is focused. For this purpose, based on the full factorial design welding simulations are performed with COMSOL. Later, the grey relational technique was used to find the contribution of these parameters. It was concluded from the full factorial method that; temperature variation is depended on the GTAW welding heat source parameters. At 95% confidence level, the width of the weld showed a major role in controlling the temperature. Moreover, the optimum combination of process variables obtained end with minimum temperature rise at a width of 0.7 mm, depth of 5.7 mm and frontal factor of 4.

Numerical simulation of nonlinear acoustic streaming in a resonator using gas-kinetic scheme

2012 ◽  
Vol 112 (8) ◽  
pp. 083501 ◽  
Author(s):  
Heying Feng ◽  
Xiaoqing Zhang ◽  
Yehui Peng ◽  
Huanxin Chen
Keyword(s):  
Numerical Simulation ◽  
Acoustic Streaming ◽  
Kinetic Scheme ◽  
Nonlinear Acoustic
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