scholarly journals Instability of a dusty Kolmogorov flow

2021 ◽  
Vol 931 ◽  
Author(s):  
Alessandro Sozza ◽  
Massimo Cencini ◽  
Stefano Musacchio ◽  
Guido Boffetta
Keyword(s):  
Numerical Analysis ◽  
Mass Fraction ◽  
Heavy Particle ◽  
Multiple Scale ◽  
Eulerian Model ◽  
Scale Separation ◽  
Kolmogorov Flow ◽  
Fluid Properties ◽  
Scale Expansion ◽  
The Stability

Suspended particles can significantly alter the fluid properties and, in particular, can modify the transition from laminar to turbulent flow. We investigate the effect of heavy particle suspensions on the linear stability of the Kolmogorov flow by means of a multiple-scale expansion of the Eulerian model originally proposed by Saffman (J. Fluid Mech., vol. 13, issue 1, 1962, pp. 120–128). We find that, while at small Stokes numbers particles always destabilize the flow (as already predicted by Saffman in the limit of very thin particles), at sufficiently large Stokes numbers the effect is non-monotonic in the particle mass fraction and particles can both stabilize and destabilize the flow. Numerical analysis is used to validate the analytical predictions. We find that in a region of the parameter space the multiple-scale expansion overestimates the stability of the flow and that this is a consequence of the breakdown of the scale separation assumptions.

scholarly journals An integral equation formulation of the N-body dielectric spheres problem. Part 1: Numerical analysis

2020 ◽  
Author(s):  
Muhammad Hassan ◽  
Benjamin Stamm
Keyword(s):  
Integral Equation ◽  
Numerical Analysis ◽  
Error Analysis ◽  
Convergence Rates ◽  
A Priori ◽  
Approximation Error ◽  
Spherical Particles ◽  
Integral Equation Formulation ◽  
Dielectric Spheres ◽  
The Stability

In this article, we analyse an integral equation of the second kind that represents the solution of N interacting dielectric spherical particles undergoing mutual polarisation. A traditional analysis can not quantify the scaling of the stability constants- and thus the approximation error- with respect to the number N of involved dielectric spheres. We develop a new a priori error analysis that demonstrates N-independent stability of the continuous and discrete formulations of the integral equation. Consequently, we obtain convergence rates that are independent of N.

scholarly journals Influence of VNIIMK 620 and Itil flax varieties on the rheological properties of wheat dough

2021 ◽  
pp. 33-36
Author(s):  
Tatyana Borisovna Kulevatova ◽  
Lyudmila Nikolaevna Zlobina ◽  
Svetlana Vitalyevna Lyascheva ◽  
Lyubov Vladimirovna Andreeva
Keyword(s):  
Wheat Flour ◽  
Mass Fraction ◽  
Absorption Capacity ◽  
Dispersed Phase ◽  
Rheological Characteristics ◽  
Water Absorption Capacity ◽  
Wheat Dough ◽  
Composite Mixture ◽  
The Stability ◽  
Torque Values

The influence of the mass fraction of flax in the composite mixture on the state of the carbohydrate – amylase complex of the studied system was studied. It was found out that the maximum viscosity of the suspension and the rate of starch gelation in a mixture of wheat flour with whole-ground flax is lower than in the suspension, where the dispersed phase was wheat flour, but higher than that, where the dispersed phase is flax. The influence of flax on the rheological characteristics of wheat dough in the Chopin+ Mixolaba protocol was revealed.  It is found out that with an increase in the mass fraction of flax in the composite mixture from 5 to 20%, the formation time of the test and its water absorption capacity increases, and the stability decreases. When the mass fraction of flax increases, the torque values at the extreme point of the function C2, which characterizes the dilution of the dough, increase; and at the point C5, which characterizes the retrogradation of starch, they decrease.  

scholarly journals The study of the properties of sweet cream butter with flavoring components

2018 ◽  
Vol 80 (3) ◽  
pp. 220-223
Author(s):  
O. I. Dolmatova ◽  
A. S. Sharshov
Keyword(s):  
Shelf Life ◽  
Mass Fraction ◽  
Maple Syrup ◽  
Warranty Period ◽  
Fatty Oil ◽  
Organoleptic Characteristics ◽  
Good Consistency ◽  
Microbiological Parameters ◽  
The Stability ◽  
Time Reserve

The technology of sweet-sour dessert oil with maple syrup has been developed. It is of scientific interest to study its quality indices when stored. The organoleptic characteristics of the butter of the sweetener with flavor components were determined in the scores. The score of the ball was 20 points. The chemical parameters of sweet dessert oil with maple syrup are found: mass fraction of fat, not less than – 62%, mass fraction of dry substances, not less – 9,5%, mass fraction of moisture, not more than – 28,5%. The conformity of oil indicators with the norms specified in TP TS 033/2013 for cream butter with the components is established: mass fraction of fat – 50 to 69%, mass fraction of moisture – 16 to 45%. The thermostability of butter of sweet-dessert dessert oil with maple syrup has been determined – 0,7, i.e. the indicator is characterized as satisfactory. A good consistency of sweet dessert oil with maple syrup is found on the slice – the plate has a dense, even surface and edges, with slight pressure bending. The shelf life of sweet dessert oil with maple syrup is 15 days. Acidity of the fat phase was determined over a period of 21 days (taking into account the time reserve). The index of acidity of the analyzed sample for 15 days was – 2.7 °C, which corresponds to the norm. Estimation of the acidity of the fatty phase and the acidity of the plasma of the oil showed an insignificant increase during the warranty period of shelf life. The stability of fatty oil of sweet-dessert dessert with maple syrup has been determined. During the experiment, the color became yellow, the smell is sweet, creamy, pleasant, the aroma of maple syrup is pronounced. The specimen withstood the test for 8 hours, no damage to the fat is noted. The microbiological parameters of the oil have been determined. The conformity of oil with the requirements of State standard 32899–2014 and TP TS 033/2013 during storage is established.

Numerical analysis of the anti-seepage measures for high earth rockfill dam on deep overburden

2012 ◽  
Vol 170-173 ◽  
pp. 1872-1877 ◽  
Author(s):  
Jun Yan ◽  
Si Hong Liu ◽  
Bin Zhou
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Seepage Field ◽  
Seepage Analysis ◽  
The Real ◽  
Rockfill Dam ◽  
The Stability ◽  
High Rockfill Dam ◽  
At Home

The anti-seepage measures of a high earth rockfill dam built on the foundation with a deep overburden affects the stability and safety of the dam greatly. Nowadays there are few researches on this area both at home and abroad. On the basis of the finite element seepage analysis of the Pubugou high rockfill dam in which core walls and two cut-off walls are designed as the anti-seepage measures, the real seepage behavior of the seepage field is obtained in this paper, as well as the seepage characters of the seepage field under different arrangements of the cut-off walls. The conclusions have a certain referential value for the design of the anti-seepage measures for the similar projects with the foundation of a deep overburden.

Dispersion of TiO2 Nanoparticles in Aqueous Solution

2018 ◽  
Vol 922 ◽  
pp. 8-13
Author(s):  
Wen Xiu Liu ◽  
Peng Sun ◽  
Jun Zhang ◽  
Wen Bin Cao
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Mass Fraction ◽  
Adsorption Mechanism ◽  
Secondary Particle ◽  
Aqueous Dispersion ◽  
Ftir Analysis ◽  
Carboxylate Groups ◽  
The Stability ◽  
Potential Test

Stable TiO2aqueous dispersion with an averaged secondary particle size of about 10 nm was achieved by using commercially available dispersant Di-7N. The stability of the dispersion was measured by Zeta-potential test. And the results showed that the optimal mass fraction of Di-7N was 12 wt%. The adsorption mechanism examined by FTIR analysis indicates that the carboxylate groups in Di-7N is absorbed on the surface of nano-TiO2particles and the adsorbed structure is proposed to be bidentate chelating.

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