Body force equivalents for seismic dislocations

1964 ◽  
Vol 54 (6A) ◽  
pp. 1875-1888 ◽  
Author(s):  
R. Burridge ◽  
L. Knopoff
Keyword(s):  
Explicit Expression ◽  
Inhomogeneous Medium ◽  
Elastic Properties ◽  
Body Force ◽  
The Body ◽  
Double Couple ◽  
Reflecting Surfaces ◽  
Seismic Dislocations

abstract An explicit expression is derived for the body force to be applied in the absence of a dislocation, which produces radiation identical to that of the dislocation. This equivalent force depends only upon the source and the elastic properties of the medium in the immediate vicinity of the source and not upon the proximity of any reflecting surfaces. The theory is developed for dislocations in an anisotropic inhomogeneous medium; in the examples isotropy is assumed. For displacement dislocation faults, the double couple is an exact equivalent body force.

scholarly journals A Result regarding the Seismic Dislocations in Microstretch Thermoelastic Bodies

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
M. Marin ◽  
O. Florea ◽  
S. R. Mahmoud
Keyword(s):  
Explicit Expression ◽  
Classical Theory ◽  
The Body ◽  
Displacement Fields ◽  
Seismic Dislocation ◽  
Elastic Bodies ◽  
Seismic Dislocations

The aim of our study is to derive a relation of De Hoop-Knopoff type for displacement fields within context of thermoelastic microstretch bodies. Then, as a consequence, an explicit expression of the body loadings equivalent to a seismic dislocation is obtained. The results are extensions of those from the classical theory of elastic bodies.

scholarly journals Computational Modeling of Vortex Generators for Turbomachinery

2002 ◽  
Author(s):  
R. V. Chima
Keyword(s):  
Computational Models ◽  
Body Force ◽  
Secondary Flows ◽  
The Body ◽  
Vortex Generators ◽  
Force Model ◽  
Suction Surface ◽  
Near Surface ◽  
Compressor Rotor ◽  
Surface Particle

In this work computational models were developed and used to investigate applications of vortex generators (VGs) to turbomachinery. The work was aimed at increasing the efficiency of compressor components designed for the NASA Ultra Efficient Engine Technology (UEET) program. Initial calculations were used to investigate the physical behavior of VGs. A parametric study of the effects of VG height was done using 3-D calculations of isolated VGs. A body force model was developed to simulate the effects of VGs without requiring complicated grids. The model was calibrated using 2-D calculations of the VG vanes and was validated using the 3-D results. Then three applications of VGs to a compressor rotor and stator were investigated: 1. The results of the 3-D calculations were used to simulate the use of small casing VGs used to generate rotor preswirl or counterswirl. Computed performance maps were used to evaluate the effects of VGs. 2. The body force model was used to simulate large partspan splitters on the casing ahead of the stator. Computed loss buckets showed the effects of the VGs. 3. The body force model was also used to investigate the use of tiny VGs on the stator suction surface for controlling secondary flows. Near-surface particle traces and exit loss profiles were used to evaluate the effects of the VGs.

Stresses and Displacements in a Rotating Conical Shell

1943 ◽  
Vol 10 (2) ◽  
pp. A53-A61
Author(s):  
J. L. Meriam
Keyword(s):  
Conical Shell ◽  
Body Force ◽  
Theory Of Elasticity ◽  
Common Type ◽  
The Body ◽  
Surface Loading ◽  
Thin Walled Structures ◽  
Special Cases ◽  
Engineering Problems ◽  
Rotating Conical Shell

Abstract The analysis of shells is an important subdivision of the general theory of elasticity, and its application is useful in the solution of engineering problems involving thin-walled structures. A common type of shell is one which possesses symmetry with respect to an axis of revolution. A theory for such shells has been developed by various investigators (1, 2, 3, 6) and applied to a few simple cases such as the cylindrical, spherical, and conical shapes. Boundary conditions, for the most part, have been simple static ones, and conditions of surface loading have been included in certain special cases. This paper extends the theory of axially symmetrical shells by including the body force of rotation about the axis and applies the results to the rotating conical shell. The analysis follows a pattern established by several investigators (1, 2, 3, 6) and for this reason is abbreviated to a considerable extent. Only where the inclusion of the body force makes elucidation advisable or where a slightly different method of approach is used are the steps presented in more detail.

The solution of the dynamic field of the Haskell fault model reconsidered

1982 ◽  
Vol 72 (4) ◽  
pp. 1069-1083
Author(s):  
R. D. List
Keyword(s):  
Half Space ◽  
Displacement Field ◽  
Body Force ◽  
Fault Model ◽  
Earthquake Source ◽  
Infinite Space ◽  
Force Method ◽  
Body Force Method ◽  
Rupture Speed ◽  
Seismic Dislocations

abstract A method of obtaining the displacement field of the Haskell model of an earthquake source, based on the well-known equivalence of seismic dislocations and body force, is described. It is shown that the solution of Madariaga (1978) can be generalized and that the two methods are equivalent for the problem of a rectangular dislocation expanding on a plane in an infinite space with a variable rupture speed and variable slip in the direction of rupture. One of the advantages of the equivalent body force method is that it can be used to readily obtain the transformed solution to the Haskell model in a half-space for a rectangular dislocation, expanding with variable rupture speed and variable slip.

A Review of Inlet-Fan Coupling Methodologies

2017 ◽  
Author(s):  
Benjamin Godard ◽  
Edouard De Jaeghere ◽  
Nabil Ben Nasr ◽  
Julien Marty ◽  
Raphael Barrier ◽  
...  
Keyword(s):  
Experimental Data ◽  
Industrial Design ◽  
Body Force ◽  
The Body ◽  
Source Terms ◽  
Force Modeling ◽  
Actuator Disc ◽  
Flow Deviation ◽  
New Challenges ◽  
Bypass Ratio

With the rise of ultra high bypass ratio turbofan and shorter and slimmer inlet geometries compared to classical architectures, designers face new challenges as nacelle and fan design cannot anymore be addressed independently. This paper reviews CFD methods developed to simulate inlet-fan interactions and suitable for industrial design cycles. In addition to the reference isolated fan and nacelle models, the methodologies evaluated in this study consist of two fan modeling approaches, an actuator disc and body-force source terms. The configuration is a modern turbofan with a high bypass ratio under cross-wind. Results are compared to experimental data. As to be predicted, the body-force modeling approach enables early inlet reattachment. In addition, it provides a representative flow deviation across the fan zone which enables performance and stability assessments.

Rack Level Modeling of Air Flow Through Perforated Tile in a Data Center

2012 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Pramod Kumar ◽  
Yogendra Joshi ◽  
Thomas S. Weiss ◽  
Gary Meyer
Keyword(s):  
Data Center ◽  
Body Force ◽  
Air Flow ◽  
The Body ◽  
Physical Models ◽  
Cfd Modeling ◽  
Computational Time ◽  
Force Model ◽  
Flow Through ◽  
Tile Surface

Effective air flow distribution through perforated tiles is required to efficiently cool servers in a raised floor data center. We present detailed computational fluid dynamics (CFD) modeling of air flow through a perforated tile and its entrance to the adjacent server rack. The realistic geometrical details of the perforated tile, as well as of the rack are included in the model. Generally models for air flow through perforated tiles specify a step pressure loss across the tile surface, or porous jump model based on the tile porosity. An improvement to this includes a momentum source specification above the tile to simulate the acceleration of the air flow through the pores, or body force model. In both of these models geometrical details of tile such as pore locations and shapes are not included. More details increase the grid size as well as the computational time. However, the grid refinement can be controlled to achieve balance between the accuracy and computational time. We compared the results from CFD using geometrical resolution with the porous jump and body force model solution as well as with the measured flow field using Particle Image Velocimetry (PIV) experiments. We observe that including tile geometrical details gives better results as compared to elimination of tile geometrical details and specifying physical models across and above the tile surface. A modification to the body force model is also suggested and improved results were achieved.

Viso-Elastic Properties of the Body-Wall of Sea Anemones

1962 ◽  
Vol 39 (3) ◽  
pp. 373-386
Author(s):  
R. MCN. ALEXANDER
Keyword(s):  
Tensile Stress ◽  
Elastic Properties ◽  
Body Wall ◽  
The Body ◽  
Polymeric System ◽  
Retardation Time ◽  
Sea Anemones

1. Creep of narcotized Metridium and Calliactis body-wall at constant tensile stress has been studied quantitatively. 2. It was found to be reversible, and seemed to be controlled by the mesogloea. Its course could be represented by equations of the formε(t)= εo+ευ(I-e-t/τ),where the retardation time τ was about 1 hr. for Metridium and many hours for Calliactis. 3. The results can most simply be explained in terms of a cross-linked and a noncross-linked polymeric system, acting in parallel. An explanation in terms of a lattice of inextensible fibres is not satisfactory. 4. The results are discussed in relation to the behaviour of the animals.

The Effect of Blade Count on Body Force Model Performance for Axial Fans

2020 ◽  
Author(s):  
Palak Saini ◽  
Jeff Defoe
Keyword(s):  
Body Force ◽  
Computational Cost ◽  
Model Performance ◽  
Aircraft Engine ◽  
The Body ◽  
Force Model ◽  
Cooling Flows ◽  
Cooling Fans ◽  
Axial Fans ◽  
Spanwise Flow

Abstract Body force models enable inexpensive numerical simulations of turbomachinery. The approach replaces the blades with sources of momentum/energy. Such models capture a “smeared out” version of the blades’ effect on the flow, reducing computational cost. The body force model used in this paper has been widely used in aircraft engine applications. Its implementation for low speed, low solidity (few blades) turbomachines, such as automotive cooling fans, enables predictions of cooling flows and component temperatures without calibrated fan curves. Automotive cooling fans tend to have less than 10 blades, which is approximately 50% of blade counts for modern jet engine fans. The effect this has on the body force model predictions is unknown and the objective of this paper is to quantify how varying blade count affects the accuracy of the predictions for both uniform and non-uniform inflow. The key findings are that reductions in blade metal blockage combined with spanwise flow redistribution drives the body force model to more accurately predict work coefficient as the blade count decreases, and that reducing the number of blades is found to have negligible impacts on upstream influence and distortion transfer in non-uniform inflow until extremely low blade counts (such as 2) are applied.

Assessment Procedure for Multiple Volumetric Flaws in p-M Diagram

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Force Method ◽  
Reference Stress ◽  
Body Force Method ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple volumetric flaws is one of the most common problems relating to pressure vessels and piping components. Under the current fitness for service rules, such as ASME, BS, and so on, multiple volumetric flaws are usually recharacterized as an enveloping volumetric flaw (defined as a single larger volumetric flaw) as well as multiple cracklike flaws, following their assessment rules. However, the rules proposed in their codes will not often agree and their justification is unknown. Furthermore, they can provide unrealistic assessment in some cases. In this paper, the interaction between two differently sized nonaligned volumetric flaws such as local thin areas is clarified by applying the body force method. Unlike multiple cracklike flaws, the effect of biaxial stresses on the interaction is evident. Based on the interaction that indicates the magnification and shielding effects and reference stress solutions, a new procedure for multiple volumetric flaws is proposed for assessing the flaws in the p-M (pressure-moment) diagram, which is a simple assessment procedure for vessels with volumetric flaws.

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