scholarly journals Numerical modeling of DC busbar contacts

2011 ◽  
Vol 24 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Ioan Popa ◽  
Alin-Iulian Dolan
Keyword(s):  
Contact Resistance ◽  
3D Model ◽  
Thermal Field ◽  
Source Term ◽  
Numerical Models ◽  
Space Distribution ◽  
Additional Source ◽  
Field Problem ◽  
Optimal Geometry ◽  
Limit Value

The paper presents two electro-thermal numerical models which can be used for the modeling and optimization of high currents busbar contacts for DC. The models are obtained by coupling of the electric model with the thermal field problem. The coupling is carried out by the source term of the differential equation which describes the thermal field. The models allows the calculation of the space distribution of the electric quantities (electric potential, the gradient of potential and the current density) and of the thermal quantities (the temperature, the temperature gradient, the Joule losses and heat flow). A heating larger than that of the busbar appears in the contact zone, caused by the contact resistance. The additional heating, caused by the contact resistance is simulated by an additional source injected on the surface of contact. The 2D model has been solved by the finite volumes method while the 3D model, by the finite elements method. Both models were experimentally validated. Using the models, one can determine the optimal geometry of dismountable contact for an imposed limit value of the temperature.

Long-term thermal two- and three-dimensional analysis of roller compacted concrete dams supported by monitoring verification

2010 ◽  
Vol 37 (4) ◽  
pp. 600-610 ◽  
Author(s):  
Vladan Kuzmanovic ◽  
Ljubodrag Savic ◽  
John Stefanakos
Keyword(s):  
Thermal Analysis ◽  
Boundary Conditions ◽  
Thermal Field ◽  
Numerical Models ◽  
Three Dimensional ◽  
Roller Compacted Concrete ◽  
Rcc Dam ◽  
Field Investigations ◽  
Good Agreement

This paper presents two-dimensional (2D) and three-dimensional (3D) numerical models for unsteady phased thermal analysis of RCC dams. The time evolution of a thermal field has been modeled using the actual dam shape, RCC technology and the adequate description of material properties. Model calibration and verification has been done based on the field investigations of the Platanovryssi dam, the highest RCC dam in Europe. The results of a long-term thermal analysis, with actual initial and boundary conditions, have shown a good agreement with the observed temperatures. The influence of relevant parameters on the thermal field of RCC dams has been analyzed. It is concluded that the 2D model is appropriate for the thermal phased analysis, and that the boundary conditions and the mixture properties are the most influential on the RCC dam thermal behavior.

An Inverse Algorithm to Estimate Spatially Varying Thermal Contact Resistance

2002 ◽  
Author(s):  
Eduardo Divo ◽  
Alain J. Kassab ◽  
Jennifer Gill
Keyword(s):  
Inverse Problem ◽  
Contact Resistance ◽  
Objective Function ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Random Noise ◽  
Surface Characteristics ◽  
Interfacial Region ◽  
Field Problem ◽  
Additional Information

Characterization of the thermal contact resistance is important in modeling of multi-component thermal systems which feature mechanically mated surfaces. Thermal resistance is phenomenologically quite complex and depends on many parameters including surface characteristics of the interfacial region and contact pressure. In general, the contact resistance varies as a function of pressure and is non-uniform along the interface. An inverse problem is formulated to estimate the variation of the contact resistance. A two-dimensional model is considered where the contact resistance is sought along the contact line at the interface between two regions. Temperature measured at discrete locations using embedded sensors placed in proximity to the interface provides the additional information required to solve the inverse problem. Given current estimates of the contact resistance as a function of position along the interface, a forward problem is solved, and a quadratic objective function is formulated to evaluate the difference between predicted temperatures at the sensors and those measured. A genetic algorithm is used to minimize the objective function and obtain the best estimate of the contact resistance. A boundary element method is used to solve the forward temperature field problem. Numerical simulations are carried out to demonstrate the approach. Random noise is used to simulate the effect of input uncertainties in measured temperatures at the sensors.

scholarly journals Review on Laser Interaction in Confined Regime: Discussion about the Plasma Source Term for Laser Shock Applications and Simulations

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2032
Author(s):  
Alexandre Rondepierre ◽  
Arnaud Sollier ◽  
Laurent Videau ◽  
Laurent Berthe
Keyword(s):  
Source Term ◽  
High Pressures ◽  
Numerical Models ◽  
Historical Review ◽  
Plasma Source ◽  
Plasma Pressure ◽  
Laser Shock ◽  
Confined Plasmas ◽  
Shock Peening ◽  
Very High

This review proposes to summarize the development of laser shock applications in a confined regime, mainly laser shock peening, over the past 50 years since its discovery. We especially focus on the relative importance of the source term, which is directly linked to plasma pressure. Discussions are conducted regarding the experimental setups, experimental results, models and numerical simulations. Confined plasmas are described and their specific properties are compared with those of well-known plasmas. Some comprehensive keys are provided to help understand the behavior of these confined plasmas during their interaction with laser light to reach very high pressures that are fundamental for laser shock applications. Breakdown phenomena, which limit pressure generation, are also presented and discussed. A historical review was conducted on experimental data, such as pressure, temperature, and density. Available experimental setups used to characterize the plasma pressure are also discussed, and improvements in metrology developed in recent years are presented. Furthermore, analytical and numerical models based on these experiments and their improvements, are also reviewed, and the case of aluminum alloys is studied through multiple works. Finally, this review outlines necessary future improvements that expected by the laser shock community to improve the estimation of the source term.

On: “Magnetic anomalies of two‐dimensional bodies in a magnetic half‐space” by E. E. S. Sampaio (GEOPHYSICS, v. 47, p. 1229–1234, August, 1982).

Geophysics ◽  
1984 ◽  
Vol 49 (10) ◽  
pp. 1800-1800
Author(s):  
L. Eskola
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Analytic Solution ◽  
Lower Boundary ◽  
Magnetic Anomalies ◽  
Additional Source ◽  
Field Problem ◽  
Susceptibility Contrast ◽  
The Magnetic Field ◽  
Upper Boundary

In a recent paper Sampaio presented an analytic solution of the magnetic field problem for a circular magnetized cylinder embedded in a homogeneous magnetized half‐space. In his paper, Sampaio also stated that the numerical method for solving magnetostatic problems by Eskola and Tervo (1980) doesn’t take into consideration the susceptibility contrast between the half‐space and the air. The model treated by Sampaio doesn’t actually exist, however. For a magnetized environment, in addition to the upper boundary, there is also a lower boundary, i.e., where the rock loses its magnetization (at least at the Curie point). This boundary holds an additional source of magnetic field that is of the same order of strength as the field caused by the upper boundary, if the horizontal dimensions of the magnetized environment are large. If the horizontal dimensions are not large, the effect of the vertical boundaries of the environment must also be taken into consideration. Eskola and Tervo (1980) find no difficulty in taking into consideration all the boundaries by means of their method.

Use of P-1 model with the additional source term for numerical simulation of ultraviolet radiation in a photoreactor

2014 ◽  
Vol 31 (6) ◽  
pp. 956-960 ◽  
Author(s):  
Baoqing Deng ◽  
Daqiang Ge ◽  
Li Lu ◽  
Di Ge ◽  
Jiajia Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Ultraviolet Radiation ◽  
Source Term ◽  
Additional Source

On the Two-Dimensional Simplification of Three-Dimensional Cementless Hip Stem Numerical Models

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Fernando J. Quevedo González ◽  
Michael Reimeringer ◽  
Natalia Nuño
Keyword(s):  
Cortical Thickness ◽  
Variable Thickness ◽  
3D Model ◽  
Numerical Models ◽  
Computational Cost ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Stair Climbing ◽  
Side Plate ◽  
2D Model

Three-dimensional (3D) finite element (FE) models are commonly used to analyze the mechanical behavior of the bone under different conditions (i.e., before and after arthroplasty). They can provide detailed information but they are numerically expensive and this limits their use in cases where large or numerous simulations are required. On the other hand, 2D models show less computational cost, but the precision of results depends on the approach used for the simplification. Two main questions arise: Are the 3D results adequately represented by a 2D section of the model? Which approach should be used to build a 2D model that provides reliable results compared to the 3D model? In this paper, we first evaluate if the stem symmetry plane used for generating the 2D models of bone-implant systems adequately represents the results of the full 3D model for stair climbing activity. Then, we explore three different approaches that have been used in the past for creating 2D models: (1) without side-plate (WOSP), (2) with variable thickness side-plate and constant cortical thickness (SPCT), and (3) with variable thickness side-plate and variable cortical thickness (SPVT). From the different approaches investigated, a 2D model including a side-plate best represents the results obtained with the full 3D model with much less computational cost. The side-plate needs to have variable thickness, while the cortical bone thickness can be kept constant.

scholarly journals A resistive extension for ideal magnetohydrodynamics

2019 ◽  
Vol 491 (4) ◽  
pp. 5510-5523
Author(s):  
Alex James Wright ◽  
Ian Hawke
Keyword(s):  
Initial Data ◽  
First Principles ◽  
Source Term ◽  
Mhd Equations ◽  
Fine Tuning ◽  
Additional Source ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Ideal Magnetohydrodynamics ◽  
Ideal Magnetohydrodynamic

ABSTRACT We present an extension to the special relativistic, ideal magnetohydrodynamic (MHD) equations, designed to capture effects due to resistivity. The extension takes the simple form of an additional source term that, when implemented numerically, is shown to emulate the behaviour produced by a fully resistive MHD description for a range of initial data. The extension is developed from first principles arguments, and thus requires no fine-tuning of parameters, meaning it can be applied to a wide range of dynamical systems. Furthermore, our extension does not suffer from the same stiffness issues arising in resistive MHD, and thus can be evolved quickly using explicit methods, with performance benefits of roughly an order of magnitude compared to current methods.

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