scholarly journals Use of a Novel Algorithm to Determine Cyclic Steady State

2006 ◽  
Vol 6 (2) ◽  
pp. 70 ◽  
Author(s):  
Luis E Razon
Keyword(s):  
Steady State ◽  
Transition Period ◽  
Computing Time ◽  
Substrate Inhibition ◽  
Simple Algorithm ◽  
Stable Steady State ◽  
Stopping Criterion ◽  
State Tests ◽  
Substrate Inhibition Kinetics ◽  
State Multiplicity

A simple algorithm originally proposed by Choong, Paterson and Scott (2002) was tested on a model of an isothermal controlled-cycled stirred tank reactor with substrate inhibition kinetics, (r = 1 ~c). In previous work, this reacting system had been shown to exhibit steady-state multiplicity. The transition period of this system to the stable steady state is sometimes characterized by very slow change followed by a very rapid convergence to the stable steady state. Tests of the Choong-Paterson-Scott algorithm showed that the feature, which prevents premature termination of the calculations prior to reaching the true steady state, is very useful for this system. However, tests of the stopping criterion showed that the other feature of reducing the computing time was not realized in this system.

scholarly journals System Approach from Biomass Combustion in Packed Bed Reactor

2007 ◽  
Vol 7 (1 & 2) ◽  
pp. 16 ◽  
Author(s):  
Anhkien Le ◽  
Le Xuan Hai ◽  
V. N. Sharifi ◽  
J. Swithenbank
Keyword(s):  
Steady State ◽  
Transition Period ◽  
Computing Time ◽  
Substrate Inhibition ◽  
Simple Algorithm ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Biomass Combustion ◽  
Stable Steady State ◽  
State Tests

A simple algorithm originally proposed by Choong, Paterson and Scott (2002) was tested on a model of an isothermal controlled-cycled stirred tank reactor with substrate inhibition kinetics, (r = 1 ~c). In previous work, this reacting system had been shown to exhibit steady-state multiplicity. The transition period of this system to the stable steady state is sometimes characterized by very slow change followed by a very rapid convergence to the stable steady state. Tests of the Choong-Paterson-Scott algorithm showed that the feature, which prevents premature termination of the calculations prior to reaching the true steady state, is very useful for this system. However, tests of the stopping criterion showed that the other feature of reducing the computing time was not realized in this system.

scholarly journals Results of the Marine Ice Sheet Model Intercomparison Project, MISMIP

2012 ◽  
Vol 6 (3) ◽  
pp. 573-588 ◽  
Author(s):  
F. Pattyn ◽  
C. Schoof ◽  
L. Perichon ◽  
R. C. A. Hindmarsh ◽  
E. Bueler ◽  
...  
Keyword(s):  
Steady State ◽  
Adaptive Mesh Refinement ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Stable Steady State ◽  
Fixed Grid ◽  
Approximate Analytical Solutions ◽  
Grounding Line ◽  
Intercomparison Project ◽  
Line Positions

Abstract. Predictions of marine ice-sheet behaviour require models that are able to robustly simulate grounding line migration. We present results of an intercomparison exercise for marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no effects of lateral buttressing). Unique steady state grounding line positions exist for ice sheets on a downward sloping bed, while hysteresis occurs across an overdeepened bed, and stable steady state grounding line positions only occur on the downward-sloping sections. Models based on the shallow ice approximation, which does not resolve extensional stresses, do not reproduce the approximate analytical results unless appropriate parameterizations for ice flux are imposed at the grounding line. For extensional-stress resolving "shelfy stream" models, differences between model results were mainly due to the choice of spatial discretization. Moving grid methods were found to be the most accurate at capturing grounding line evolution, since they track the grounding line explicitly. Adaptive mesh refinement can further improve accuracy, including fixed grid models that generally perform poorly at coarse resolution. Fixed grid models, with nested grid representations of the grounding line, are able to generate accurate steady state positions, but can be inaccurate over transients. Only one full-Stokes model was included in the intercomparison, and consequently the accuracy of shelfy stream models as approximations of full-Stokes models remains to be determined in detail, especially during transients.

Metabolic flux analysis of hybridoma continuous culture steady state multiplicity

1999 ◽  
Vol 63 (6) ◽  
pp. 675-683 ◽  
Author(s):  
Brian D. Follstad ◽  
R. Robert Balcarcel ◽  
Gregory Stephanopoulos ◽  
Daniel I. C. Wang
Keyword(s):  
Steady State ◽  
Continuous Culture ◽  
Metabolic Flux Analysis ◽  
Metabolic Flux ◽  
Flux Analysis ◽  
State Multiplicity

scholarly journals A NOVEL SIMPLE-BASED PRESSURE-ENTHALPY COUPLING SCHEME FOR ENGINE FLOW PROBLEMS

2012 ◽  
Vol 17 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Maximilian Emans ◽  
Zoran Žunič ◽  
Branislav Basara ◽  
Sergey Frolov
Keyword(s):  
Linear Equations ◽  
Computing Time ◽  
Simple Algorithm ◽  
Variable Density ◽  
Coupling Scheme ◽  
The Novel ◽  
Simple Method ◽  
Flow Problems ◽  
Novel Method ◽  
Coupling Terms

A novel method in CFD derived from the SIMPLE algorithm is presented. Instead of solving the linear equations for each variable and the pressurecorrection equation separately in a so-called segregated manner, it relies on the solution of a linear system that comprises the discretisation of enthalpy and pressurecorrection equation which are linked through physical coupling terms. These coupling terms reflect a more accurate approximation of the density update with respect to thermodynamics (compared to standard SIMPLE method). We show that the novel method is a reasonable extension of existing CFD techniques for variable density flows based on SIMPLE. The novel method leads to a reduction of the number of iterations of SIMPLE which translates in many – but not in all – cases to a reduction in computing time. We will therefore demonstrate practical advantages and restrictions in terms of computational efficiency for industrial CFD applications in the field of piston engine simulations.

Sign in / Sign up

Export Citation Format

Share Document