Calculation of Polymer Flow Using Micro-Macro Simulations

2004 ◽  
Author(s):  
Kathleen Feigl ◽  
Deepthika C. Senaratne
Keyword(s):  
Experimental Data ◽  
Evolution Equations ◽  
Qualitative Behavior ◽  
Simulation Techniques ◽  
Pressure Fields ◽  
Model Dynamics ◽  
Polymer Configurations ◽  
Gaussian Stochastic Processes ◽  
Reptation Theory ◽  
Compute Velocity

A micro-macro simulation algorithm for the calculation of polymeric flow is developed and implemented. The algorithm couples standard finite element techniques to compute velocity and pressure fields with stochastic simulation techniques to compute polymer stress from simulated polymer dynamics. The polymer stress is computed using a microscopic-based rheological model which combines aspects of network and reptation theory with aspects of continuum mechanics. The model dynamics include two Gaussian stochastic processes each of which is destroyed and regenerated according to a survival time randomly generated from the material’s relaxation spectrum. The Eulerian form of the evolution equations for the polymer configurations are spatially discretized using the discontinuous Galerkin method. The algorithm is tested on benchmark contraction domains for a polyisobutylene (PIB) solution. In particular, the flow in the abrupt die entry domain is simulated and the simulation results are compared with experimental data. The results exhibit the correct qualitative behavior of the polymer and agree well with the experimental data.

Calculation of the Die Entry Flow of a Concentrated Polymer Solution Using Micro-Macro Simulations

2005 ◽  
Vol 128 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Kathleen Feigl ◽  
Deepthika C. Senaratne
Keyword(s):  
Experimental Data ◽  
Evolution Equations ◽  
Qualitative Behavior ◽  
Simulation Techniques ◽  
Pressure Fields ◽  
Model Dynamics ◽  
Polymer Configurations ◽  
Gaussian Stochastic Processes ◽  
Reptation Theory ◽  
Compute Velocity

A micro-macro simulation algorithm for the calculation of polymeric flow is developed and implemented. The algorithm couples standard finite element techniques to compute velocity and pressure fields with stochastic simulation techniques to compute polymer stress from simulated polymer dynamics. The polymer stress is computed using a microscopic-based rheological model that combines aspects of network and reptation theory with aspects of continuum mechanics. The model dynamics include two Gaussian stochastic processes, each of which is destroyed and regenerated according to a survival time randomly generated from the material’s relaxation spectrum. The Eulerian form of the evolution equations for the polymer configurations is spatially discretized using the discontinuous Galerkin method. The algorithm is tested on benchmark contraction domains for a polyisobutylene solution. In particular, the flow in the abrupt die entry domain is simulated and the simulation results are compared to experimental data. The results exhibit the correct qualitative behavior of the polymer and agree well with the experimental data.

Advanced Dryout Correlation for BWR Fuel

2010 ◽  
Author(s):  
D. Paramonov ◽  
C. Adamsson
Keyword(s):  
Experimental Data ◽  
Regression Coefficients ◽  
Qualitative Behavior ◽  
Empirical Correlations ◽  
Operational Space ◽  
Power Profile ◽  
Fuel Design ◽  
New Form ◽  
Additional Value ◽  
Dry Out

Each BWR fuel design requires a method to predict its dryout performance in order to be licensed. Presently, the assessment of dry-out risk is based on empirical correlations, which sometimes results in inaccurate or non-physical predictions in certain portions of operational space. This poses a number of limitations as plant operators seek to extract additional value from the fuel through more aggressive operation strategies. A new form of BWR dryout correlation is developed. Accuracy of predictions outside of experimental data range is increased by employing a non-linear correlation form and the transformation to axial power profile, which is based on physical considerations. Proper qualitative behavior is assured by the correlation form itself rather than values of regression coefficients.

Interpretation of Mechanical Testing Measurements for Pastes

2002 ◽  
Author(s):  
Robert A. Basterfield ◽  
Chris J. Lawrence ◽  
Michael J. Adams
Keyword(s):  
Experimental Data ◽  
Numerical Models ◽  
Experimental Methods ◽  
Published Data ◽  
The Finite Element Method ◽  
Material Parameters ◽  
Simulation Techniques ◽  
Manufacturing Sectors ◽  
Product Forms ◽  
Computer Simulation Techniques

Pastes occur as intermediates or final product forms in many industrially important manufacturing sectors. The use of computer simulation techniques, such as the finite element method, is becoming more common in the design of paste processing operations. A major problem in the application of this approach is the development of sufficiently representative materials models. It has been established that pastes may be described as elasto-viscoplastic materials with the plastic flow being governed by the Herschel-Bulkley relationship. This paper describes the development of analytical and numerical models that can be used as a basis for deriving the material parameters from experimental data obtained using extrusion, compression and bending procedures. Measurements have also been carried out on a model paste and the derived material parameters are compared with published data for the same paste. The merits of the three experimental methods are compared on this basis.

scholarly journals Qualitative behavior of stiff ODEs through a stochastic approach

2020 ◽  
Vol 10 (2) ◽  
pp. 181-187
Author(s):  
Hande Uslu ◽  
Murat Sari ◽  
Tahir Cosgun
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Real Life ◽  
Stochastic Approach ◽  
Computational Time ◽  
Qualitative Behavior ◽  
Computational Error ◽  
Linear Ordinary Differential Equations ◽  
Stiff Ordinary Differential Equations ◽  
Simulation Techniques

In the last few decades, stiff differential equations have attracted a great deal of interest from academic society, because much of the real life is covered by stiff behavior. In addition to importance of producing model equations, capturing an exact behavior of the problem by dealing with a solution method is also handling issue. Although there are many explicit and implicit numerical methods for solving them, those methods cannot be properly applied due to their computational time, computational error or effort spent for construction of a structure. Therefore, simulation techniques can be taken into account in capturing the stiff behavior. In this respect, this study aims at analyzing stiff processes through stochastic approaches. Thus, a Monte Carlo based algorithm has been presented for solving some stiff ordinary differential equations and system of stiff linear ordinary differential equations. The produced results have been qualitatively and quantitatively discussed.

scholarly journals Bending and Position Hysteresis of Magnetic Microfibers in Nonuniform Magnetic Fields

2012 ◽  
Vol 7 (2_suppl) ◽  
pp. 155892501200702 ◽  
Author(s):  
Richard E. Groff ◽  
Meng Li ◽  
Harshwardhan Karve ◽  
Alexander Tokarev ◽  
Kostantin G. Kornev
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Magnetic Properties ◽  
Model Simulation ◽  
Ritz Method ◽  
Polymer Fibers ◽  
Qualitative Behavior ◽  
Nonuniform Field ◽  
Local Minima ◽  
Hysteresis Behavior

Magnetic microfibers are fibers that behave as a flexible paramagnetic body, for example, polymer fibers filled with superparamagnetic particles. A cantilevered magnetic microfiber will bend in response to an applied magnetic field. In a nonuniform field, generated for example by a single electromagnet or by a magnetic dipole, a magnetic microfiber displays position hysteresis as the field strength increases and decreases. This paper presents a model for determining stable shapes of a cantilevered magnetic microfiber in a nonuniform magnetic field. The model determines stable shapes by finding local minima of the potential energy using a Rayleigh-Ritz method. The model predicts the position hysteresis behavior observed in magnetic microfibers. Experimental data ware collected using two electromagnets with different geometries. The model simulation and experimental data compare well both qualitatively and quantitatively. The model will be useful for designing actuators based on magnetic microfibers and for characterizing the magnetic properties of fabricated fibers. A rigid bar model is also introduced, which captures the qualitative behavior of the fiber and illustrates the source of the position hysteresis behavior.

Computer simulation of aqueous pore fluids in 2:1 clay minerals

1998 ◽  
Vol 62 (5) ◽  
pp. 657-667 ◽  
Author(s):  
N. T. Skipper
Keyword(s):  
Experimental Data ◽  
Water Systems ◽  
Atomistic Simulations ◽  
Computational Techniques ◽  
Simulation Studies ◽  
Molecular Models ◽  
Pore Fluids ◽  
Future Prospects ◽  
Simulation Techniques ◽  
Comparison With Experimental Data

AbstractMonte Carlo and molecular dynamics computer simulations are now able to provide detailed information concerning the structure, dynamics, and thermodynamics of pore fluids in 2:1 clays. This article will discuss interparticle interaction potentials currently available for atomistic simulations of clay-water systems, and will describe how computational techniques can be applied to modelling of clay systems. Some recent simulation studies of 2:1 clay hydration will then be reviewed. Comparison with experimental data promotes confidence in the molecular models and simulation techniques, and points to exciting future prospects.

Numerical Simulation on Wave Force Acting on the Hollow Blocks

2013 ◽  
Vol 702 ◽  
pp. 37-43
Author(s):  
Xue Feng Chen ◽  
Kang Yang ◽  
Yu Cheng Li
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Mathematical Model ◽  
Wave Force ◽  
Regular Wave ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Pressure Fields ◽  
Hollow Block ◽  
Numerical Wave

In order to study the wave force acting on the hollow blocks structures locating at the permeable foundation under the regular wave flume, the wave tank is established basing on improved N-S Equations. And the moving boundary’s generating wave and wave absorption of momentum source are adopted in the numerical wave flume. It can also be simulated permeable foundation by porous media module. Then mathematical model can be constructed under the interaction between waves and hollow block when PISO is used to couple velocity and pressure fields. At the same time, the numerically calculated results of the wave force acting on the hollow blocks are compared with the experimental data in agreement. In conclusion, the variation of the wave force with incident wave height and period is obtained through the numerical calculation.

scholarly journals A poro-viscoelastic substitute model of fine-scale poroelasticity obtained from homogenization and numerical model reduction

2020 ◽  
Vol 65 (4) ◽  
pp. 1063-1083 ◽  
Author(s):  
Ralf Jänicke ◽  
Fredrik Larsson ◽  
Kenneth Runesson
Keyword(s):  
Numerical Model ◽  
Model Reduction ◽  
Evolution Equations ◽  
Present Model ◽  
Scale Model ◽  
Reduced Basis ◽  
Pressure Fields ◽  
Linearly Independent ◽  
Macro Scale ◽  
Scale Fluctuation

AbstractNumerical model reduction is exploited for computational homogenization of the model problem of a poroelastic medium under transient conditions. It is assumed that the displacement and pore pressure fields possess macro-scale and sub-scale (fluctuation) parts. A linearly independent reduced basis is constructed for the sub-scale pressure field using POD. The corresponding reduced basis for the displacement field is constructed in the spirit of the NTFA strategy. Evolution equations that define an apparent poro-viscoelastic macro-scale model are obtained from the continuity equation pertinent to the RVE. The present model represents an extension of models available in literature in the sense that the pressure gradient is allowed to have a non-zero macro-scale component in the nested $$\hbox {FE}^2$$FE2 setting. The numerical results show excellent agreement between the results from numerical model reduction and direct numerical simulation. It was also shown that even 3D RVEs give tractable solution times for full-fledged $$\hbox {FE}^2$$FE2 computations.

Application of Incomplete Measurement Data to Thermal Diagnostics of Complex Power Systems Components

2000 ◽  
Author(s):  
Jerzy Gluch ◽  
Jerzy Krzyzanowski
Keyword(s):  
Experimental Data ◽  
Power Systems ◽  
Measurement Data ◽  
Measuring System ◽  
Diagnostic Tools ◽  
Power Cycle ◽  
Simulation Techniques ◽  
Complex Power ◽  
Incomplete Measurement ◽  
Thermal Diagnostics

Proper exploitation of the complex power systems needs application of diagnostic tools. The diagnostics of power systems can be effective only if reliable simulation methods are available and experimental data are complete. Unlike that last requirement, it occurs very often in practice that experimental data for particular power cycle components are incomplete. This can happen due to - inadequate distribution of measuring devices, or - particular design of the power cycle components which makes the measurement difficult or impossible. The question arises if any thermal diagnostics of components measured under such condition is possible. The authors try to answer the question taking as an example a specific subsystem of complex power cycle. It is composed of two HP turbine groups of stages, control stage and some glands of the turbine. Making use of the simulation techniques, the authors investigate how much the degradation causes of the elements of this subsystem influences the degradation symptoms of the power cycle. The answer to this question can be of significant importance for the designer of the measuring system and for the user of his thermal diagnostics efforts.

Analysis and Evaluation of Artillery Fire Simulation Test

2014 ◽  
Vol 620 ◽  
pp. 632-637 ◽  
Author(s):  
Ting Gao ◽  
Chi He ◽  
Zhao Jun Fan ◽  
Hong Li Guo
Keyword(s):  
Experimental Data ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Research Direction ◽  
Simulation Test ◽  
Analysis And Evaluation ◽  
Simulation Techniques ◽  
Test Technology ◽  
Hierarchy Process ◽  
Similar Dynamic

The artillery test of firing simulation provides the similar dynamic recoil effects of artillery, by means except firing. It is more safe and convenient with less ammunition and time consumed. This document describes the meaning and content of the artillery test of firing simulation. It analyses the feasibility of this test technology by calculating and comparing the experimental data of guns and makes a research and analysis for current situation and development of the related technology In the domestic and overseas. Through fuzzy comprehensive evaluation (FCE) and analysis hierarchy process (AHP), a comprehensive assessment on different simulation techniques is done. A research direction on the artillery test of firing simulation is proposed, which can meet the requirements of the development of modern artillery.

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