scholarly journals Energy conservation and numerical stability for the reduced MHD models of the non-linear JOREK code

2015 ◽  
Vol 49 (5) ◽  
pp. 1331-1365 ◽  
Author(s):  
Emmanuel Franck ◽  
Matthias Hölzl ◽  
Alexander Lessig ◽  
Eric Sonnendrücker
Keyword(s):  
Energy Conservation ◽  
Numerical Stability ◽  
Non Linear

A dynamic simplified Lund model for large-eddy simulation and its application to a centrifugal pump

2018 ◽  
Vol 35 (7) ◽  
pp. 2577-2588 ◽  
Author(s):  
Xianbei Huang ◽  
Baoyun Qiu ◽  
Qiang Guo ◽  
Zhuqing Liu ◽  
Wei Yang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Structure ◽  
Numerical Stability ◽  
Large Scale ◽  
Internal Flow ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Content Type ◽  
New Model ◽  
Non Linear

Purpose Construct a new sub-grid scale (SGS) model which can improve the efficiency and maintain comparative accuracy comparing to the existing dynamic cubic non-linear SGS model (DCNM). Design/methodology/approach The polynomial constitutive relation between the SGS stress tensor and both strain and rotation rate is selected as a basement. Simplification is achieved by eliminating the solid-body rotation term and adopting the assumption proposed by Kosovic. A dynamic procedure is applied to calculate three model coefficients in the new model. The new model (named dynamic simplified Lund model) and DCNM are applied to the rotating channel flow and the internal flow in a centrifugal pump impeller to examine the performance. Findings The new model is as accurate as DCNM but decreases 25 per cent computational resources. The ability of capturing rotation effect and reflecting backscatter is verified through cases. In addition, good numerical stability is shown during the calculation. Research limitations/implications More benchmark and engineering cases should be used to get further confidence on the new model. Practical implications The new model is promising in industrial application with the advantage of both accuracy and efficiency. For the flow with large-scale separation or more complicate phenomenon, the model is thought to give accurate flow structure. Originality/value A new non-linear SGS model is proposed in this paper. The accuracy, numerical stability and efficiency are validated for this model. Therefore, it is promising in the prediction of the flow structure in centrifugal pumps.

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

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