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91.
Plane surface suddenly set in motion in a viscoelastic fluid with fractional Maxwell model 总被引:6,自引:0,他引:6
The fractional calculus approach in the constitutive relationship model of viscoelastic fluid is introduced. The flow near
a wall suddenly set in motion is studied for a non-Newtonian viscoelastic fluid with the fractional Maxwell model. Exact solutions
of velocity and stress are obtained by using the discrete inverse Laplace transform of the sequential fractional derivatives.
It is found that the effect of the fractional orders in the constitutive relationship on the flow field is significant. The
results show that for small times there are appreciable viscoelastic effects on the shear stress at the plate, for large times
the viscoelastic effects become weak.
The project supported by the National Natural Science Foundation of China (10002003), Foundation for University Key Teacher
by the Ministry of Education, Research Fund for the Doctoral Program of Higher Education 相似文献
92.
广义Maxwell黏弹性流体在两平板间的非定常流动 总被引:2,自引:0,他引:2
将分数阶微积分运算引入Maxwell黏弹性流体的本构方程,研究了黏弹性流体在两平板问的非定常流动.对于广义Maxwell黏弹性流体的分数阶导数模型,导出了对时间具有分数阶导数的特殊运动方程,利用分数阶微积分的Laplace变换理论,得到了流动的解析解. 相似文献
93.
M. Emin Erdo
an 《International Journal of Non》1999,34(6):660
An exact solution of the Navier–Stokes equations is obtained for the flow between two eccentric disks rotating with the same angular velocity and one of them executing non-torsional oscillations. An analytical solution describing the flow at large and small times after the start is given. The solutions depend on the ratio of the frequency of oscillation to the angular velocity of the disks and the ratio of the amplitude of oscillation to the angular velocity of the disks and to the distance between the axes of rotation, and the Reynolds number based on the distance between the disks and the angular velocity of the disks. The solutions for three cases when the angular velocity is greater than the frequency of oscillation or it is smaller than the frequency or it is equal to the frequency are discussed. 相似文献
94.
In a previous article the authors introduced a Lagrange multiplier based fictitious domain method. Their goal in the present article is to apply a generalization of the above method to: (i) the numerical simulation of the motion of neutrally buoyant particles in a three-dimensional Poiseuille flow; (ii) study – via direct numerical simulations – the migration of neutrally buoyant balls in the tube Poiseuille flow of an incompressible Newtonian viscous fluid. Simulations made with one and several particles show that, as expected, the Segré–Silberberg effect takes place. To cite this article: T.-W. Pan, R. Glowinski, C. R. Mecanique 333 (2005). 相似文献
95.
A mathematical model has been developed for the simulation of gas-particle flow and fluid catalytic cracking in downer reactors. The model takes into account both cracking reaction and flow behavior through a four-lump reaction kinetics coupled with two-phase turbulent flow. The prediction results show that the relatively large change of gas velocity affects directly the axial distribution of solids velocity and void fraction, which significantly interact with the chemical reaction. Furthermore, model simulations are carried out to determine the effects of such parameters on product yields, as bed diameter, reaction temperature and the ratio of catalyst to oil, which are helpful for optimizing the yields of desired products. The model equations are coded and solved on CFX4.4. 相似文献
96.
M. Zidan 《Rheologica Acta》1981,20(4):324-333
Summary Using elliptic coordinates, the flow pattern of a fluid of grade four between two elliptic tubes is determined. A comparison between the position of the maximum of the axial velocity in the present case and in the case of two concentric circular tubes shows a basic difference. In the elliptic case the maximum is shifted towards the external wall, while in the case of concentric circular tubes the shift is in the direction of the internal wall. The secondary flow shows dissymmetry with reference to the intermediate line
, which itself lies nearer to the external wall.
A planar domain representing the annular region - vector inx 1,x 2-plane - x i rectangular coordinates - rectangular unit vectors - , elliptic coordinates - 1, 2 ellipses representing respectively the internal and external tubes - = 2 – 1 annular widthy = ( – 1)/ - µ 1st grade material constant - i 2nd grade material constants - i 3rd grade material constants - i 4th grade material constants - I unit tensor - T E extra stress (T + pI) - V potential of body forces - material density = (p/) + V = –ax 3 + () - a specific driving force - arbitrary scalar function - A k Rivlin-Eriksen tensors - S stress scalar defined onA - t stress vector defined onA - P stress tensor defined onA - v axial velocity - v i i th term in the approximation ofv - u velocity vector perpendicular to the axis 4( 3 + 4 + 5 + 1/26) –2/µ(2 1 + 2)( 2 + 3) - T stress tensor - p arbitrary hydrostatic pressure - u i i th term in the approximation ofu - stream function definingu - i i th term in the approximation of With 8 figures and 1 table 相似文献
Zusammenfassung Unter Benutzung elliptischer Koordinaten wird die Strömung zwischen zwei elliptischen Rohren bestimmt. Ein Vergleich zwischen der Lage des axialen Geschwindigkeitsmaximums im vorliegenden Fall und im Fall zweier konzentrischer Kreisrohre ergibt einen grundsätzlichen Unterschied: Das Maximum ist im elliptischen Fall zur äußeren Wand hin verschoben, während die Verschiebung im Fall der konzentrischen Kreisrohre zur inneren Wand hin erfolgt. Die Sekundärströmung ist unsymmetrisch relativ zur mittleren Stromlinie , die selbst näher zur äußeren Wand liegt.
A planar domain representing the annular region - vector inx 1,x 2-plane - x i rectangular coordinates - rectangular unit vectors - , elliptic coordinates - 1, 2 ellipses representing respectively the internal and external tubes - = 2 – 1 annular widthy = ( – 1)/ - µ 1st grade material constant - i 2nd grade material constants - i 3rd grade material constants - i 4th grade material constants - I unit tensor - T E extra stress (T + pI) - V potential of body forces - material density = (p/) + V = –ax 3 + () - a specific driving force - arbitrary scalar function - A k Rivlin-Eriksen tensors - S stress scalar defined onA - t stress vector defined onA - P stress tensor defined onA - v axial velocity - v i i th term in the approximation ofv - u velocity vector perpendicular to the axis 4( 3 + 4 + 5 + 1/26) –2/µ(2 1 + 2)( 2 + 3) - T stress tensor - p arbitrary hydrostatic pressure - u i i th term in the approximation ofu - stream function definingu - i i th term in the approximation of With 8 figures and 1 table 相似文献
97.
The sloshing problem is considered in a half-space covered by a rigid dock with apertures. The dependence of the fundamental sloshing frequency on the shape of the free surface region is studied. It is proved that the inequality holds between the fundamental eigenvalues corresponding to two different regions if some conditions are fulfilled. These conditions are verified for particular classes of regions of a fixed area in order to demonstrate that the disk yields the maximum of the fundamental eigenvalue for each of these classes. On the other hand, examples of regions are constructed for which the fundamental eigenfrequency is larger than that for the circular aperture of the same area and even as large as one wishes. To cite this article: V. Kozlov, N. Kuznetsov, C. R. Mecanique 330 (2002) 723–728. 相似文献
98.
The effect of a non-uniform parallel high magnetic field on flow control characteristics is investigated experimentally for a magnetic fluid single-phase flow and an air—magnetic fluid two-phase flow in a vertical channel. It is found that as the magnetic field strength is increased, the friction factor of the single-phase flow increases significantly. For the two-phase flow, the friction pressure loss and the head pressure loss, which is smaller than the friction loss, are negligibly small compared with the magnetic pressure loss. In the case where air is injected 27.9d upstream from the maximum magnetic field, the air flow is blocked by the magnetic force in the entrance of the magnetic field, which leads to increases in both local void fraction and pressure drop there. In the case where air is injected 1.43d downstream from the maximum magnetic field, the air flow is accelerated, resulting in a decrease in void fraction and an increase in pressure rise. In the latter case and under the present range of experimental conditions, the magnetic pumping head reaches 0.02 MPa at the highest, and the maximum circulation flow rate reaches twice as high as non-magnetically driven flow rate. 相似文献
99.
A squeezing property inL
2() is established for orbits of the semigroup associated with the equations of motion of a nonlinear incompressible bipolar viscous fluid; it is assumed that=[0,L]
n
,n=2 or 3,L>0, and that the velocity vector satisfies a spatial periodicity condition. The proof depends, in an essential manner, on key estimates for both the nonlinear operator generated by the nonlinear viscosity term in the model and the time integral of theH
3() norm of the velocity. 相似文献
100.