Numerical Studies of the Influence of Heterogeneity on Rock Failure and Induced Earthquake Precursors

2005 ◽  
Vol 297-300 ◽  
pp. 2648-2653
Author(s):  
Ming Ruo Jiao ◽  
Chun An Tang ◽  
W.F. Sun ◽  
Shu Hong Wang
Keyword(s):  
Numerical Simulations ◽  
Rock Failure ◽  
Earthquake Precursors ◽  
Numerical Results ◽  
Mechanical Heterogeneity ◽  
Induced Earthquake ◽  
Numerical Studies ◽  
Good Agreement

A series of numerical simulations were performed to investigate the effects of geometric and mechanical heterogeneity of pre-existing faults of rocks on their failure and induced earthquake precursors. The numerical results revealed that rock failures with the different heterogeneity produce the different earthquake precursors, which are in a good agreement with those of observations in nature.

scholarly journals Liquid interfaces in viscous straining flows: numerical studies of the selective withdrawal transition

2008 ◽  
Vol 613 ◽  
pp. 171-203 ◽  
Author(s):  
MARKO KLEINE BERKENBUSCH ◽  
ITAI COHEN ◽  
WENDY W. ZHANG
Keyword(s):  
Steady State ◽  
Dynamic Range ◽  
Model Problem ◽  
Numerical Results ◽  
Experimental Measurements ◽  
Liquid Interfaces ◽  
Selective Withdrawal ◽  
Interface Evolution ◽  
Numerical Studies ◽  
Good Agreement

This paper presents a numerical analysis of the transition from selective withdrawal to viscous entrainment. In our model problem, an interface between two immiscible layers of equal viscosity is deformed by an axisymmetric withdrawal flow, which is driven by a point sink located some distance above the interface in the upper layer. We find that steady-state hump solutions, corresponding to selective withdrawal of liquid from the upper layer, cease to exist above a threshold withdrawal flux, and that this transition corresponds to a saddle-node bifurcation for the hump solutions. Numerical results on the shape evolution of the steady-state interface are compared against previous experimental measurements. We find good agreement where the data overlap. However, the larger dynamic range of the numerical results allows us to show that the large increase in the curvature of the hump tip near transition is not consistent with an approach towards a power-law cusp shape, an interpretation previously suggested from inspection of the experimental measurements alone. Instead, the large increase in the curvature at the hump tip reflects a robust trend in the steady-state interface evolution. For large deflections, the hump height is proportional to the logarithm of the curvature at the hump tip; thus small changes in hump height correspond to large changes in the value of the hump curvature.

Investigation on trim control of semi-planing amphibious cargo truck using experimental and numerical approaches

2021 ◽  
pp. 095440622110214
Author(s):  
Chengliang Sun ◽  
Xiaojun Xu ◽  
Tengan Zou
Keyword(s):  
Experimental Tests ◽  
Numerical Results ◽  
Maximum Speed ◽  
Key Indicator ◽  
Numerical Studies ◽  
Resistance Reduction ◽  
Speed Up ◽  
Good Agreement ◽  
Numerical Approaches

Speed on water is a key indicator of amphibious vehicles. However, due to the inherent non-streamlined configuration, when reaching a certain velocity, the resistance acting on the vehicle hull is so large and the maximum speed on water is hard to be further enhanced. Moreover, the trim gets so larger that leads the stern submerged into water when speed up. In order to solve this problem of a semi-planing amphibious cargo truck, this paper proposed a method by installing interceptors, hydrofoils, and combination of them on the stern. Experimental tests and numerical studies were performed respectively, and the numerical results were in good agreement with experiment. In what continues, the effect of interceptors, hydrofoils, and combination of them on trim and resistance was investigated. The results showed that the interceptor had a better effect than hydrofoil when height is not so big, but the effect got more and more powerful with interceptor height increasing, finally lead to an excessive trim control. Combination of interceptor with hydrofoil in suitable size were beneficial to trim control and resistance reduction.

On the Use of Commercial CFD Software in the Study of Unsteady Aerodynamic Flows Around Oscillating Airfoils

2006 ◽  
Author(s):  
Bamidele A. Sangolola ◽  
Stephen P. Lakey
Keyword(s):  
Numerical Simulations ◽  
Experimental Work ◽  
Flow Conditions ◽  
Flow Solver ◽  
Unsteady Aerodynamic ◽  
Numerical Studies ◽  
Attached Flow ◽  
Mach Numbers ◽  
Naca 0012 ◽  
Good Agreement

Numerical simulations have been conducted to simulate the flow over an oscillating NACA 0012 airfoil operating at various Mach numbers, oscillatory frequencies and mean angles of attack, for nominally attached flow conditions. The simulations have been carried out using the ANSYS-CFX5 flow solver, to assess the performance of this tool in conducting unsteady aerodynamic analysis of this nature. Numerical results are compared to the experimental work of Landon, and discussed in relation to previous numerical studies. Overall a good agreement is found for the majority of cases, however, a number of discrepancies have been noted and discussed, particularly regarding simulation of high mean incidence angles and subsonic Mach numbers.

Nonlinear Structure and Halo Formation

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Numerical Simulations ◽  
Computational Methods ◽  
Computer Technology ◽  
Nonlinear Evolution ◽  
Theoretical Calculations ◽  
Nonlinear Structure ◽  
Numerical Studies ◽  
Analytic Models ◽  
Shed Light ◽  
Good Agreement

This chapter studies the evolution of perturbations in the nonlinear regime. It focuses for the most part on analytic models that shed light on the physical processes involved. The advent of computer technology has made numerical studies of nonlinear evolution almost routine, and many of today's theoretical calculations follow this path. The analytic approaches described here inform these calculations, but the numerical simulations help to sharpen this chapter's conclusions and predictions. The chapter discusses this synergy and describes “semianalytic” models that can be written analytically but whose ultimate justification lies in their good agreement with numerical simulations. It also describes the fundamental aspects of computational methods.

The laminar free surface boundary layer of a solitary wave

2012 ◽  
Vol 696 ◽  
pp. 423-433 ◽  
Author(s):  
Christian A. Klettner ◽  
Ian Eames
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Solitary Wave ◽  
Numerical Simulations ◽  
Numerical Results ◽  
Analytical Models ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Good Agreement

AbstractThe laminar free surface boundary layer beneath a solitary wave is investigated using numerical simulations. Across the boundary layer $\partial {u}_{s} / \partial {x}_{n} $ and $\partial {u}_{n} / \partial {x}_{s} $ are comparable in magnitude, where $u$ is the velocity, $x$ position and subscripts $s$ and $n$ refer to components tangential and normal to the free surface. In this region $\partial {u}_{n} / \partial {x}_{s} $ is approximately constant across the boundary layer while $\partial {u}_{s} / \partial {x}_{n} $ varies with ${x}_{n} $ and outside the boundary layer tends to ${\ensuremath{-} } \mathop{ (\partial {u}_{s} / \partial {x}_{n} )} \nolimits _{n= 0} $. The numerical results are compared to analytical models and good agreement is found.

Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

2018 ◽  
Vol 55 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Gabriel Murariu ◽  
Razvan Adrian Mahu ◽  
Adrian Gabriel Murariu ◽  
Mihai Daniel Dragu ◽  
Lucian P. Georgescu ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Unmanned Aerial Vehicle ◽  
Numerical Study ◽  
Flight Time ◽  
Cluster System ◽  
Numerical Results ◽  
Operational Performance ◽  
Gliding Flight ◽  
Aerial Vehicle ◽  
Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

2021 ◽  
pp. 875608792110260
Author(s):  
ME Ismail ◽  
MM Awad ◽  
AM Hamed ◽  
MY Abdelaal ◽  
EB Zeidan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Film Cooling ◽  
Radiation Heat Transfer ◽  
Absolute Error ◽  
Numerical Results ◽  
Upper Lip ◽  
Original Design ◽  
Blown Film ◽  
Set Up

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

On Wall Effects in Cavity Flows

1984 ◽  
Vol 28 (01) ◽  
pp. 70-75
Author(s):  
C. C. Hsu
Keyword(s):  
Numerical Results ◽  
Cavity Flows ◽  
Two Dimensional ◽  
Wall Effects ◽  
Free Jet ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
Good Agreement

Simple wall correction rules for two-dimensional and nearly two-dimensional cavity flows in closed or free jet water tunnels, based on existing linearized analyses, are made. Numerical results calculated from these expressions are compared with existing experimental findings. The present theoretical predictions are, in general, in good agreement with data.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

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