scholarly journals On the K-th Power of Stokes Operator

2020 ◽  
Vol 63 (1) ◽  
pp. 1-10
Author(s):  
Eleftherios Protopapas ◽  

Stokes operators, are well known partial differential operators of elliptic type, which are often used in Applied Mathematics. Stokes equation describes the irrotational, axisymmetric creeping flow and Stokes bi-stream equation denotes the rotational one, where Necessary and sufficient conditions for the separability and the R-separability of the equation have been proved recently. Moreover, the 0-eigenspace and the generalized 0-eigenspace of the operator have been derived in several coordinate systems. Specifically, the spherical coordinate system is employed in many problems taking into account that in many engineering applications, the solutions in spherical geometry seem to be adequate for solving a problem. In the present manuscript, it is shown that equation admits a solution of the form where are solutions of Stokes equation and r is the radial spherical variable. Additionally, we obtain the kernel of the k-th power of the Stokes operator, in the spherical geometry for every

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 249
Author(s):  
Goce Koleski ◽  
Thomas Bickel

We consider the creeping flow of a Newtonian fluid in a hemispherical region. In a domain with spherical or nearly spherical geometry, the solution of the Stokes equation can be expressed as a series of spherical harmonics. However, the original Lamb solution is not complete when the flow is restricted to a semi-infinite space. The general solution in hemispherical geometry is then constructed explicitly. As an application, we discuss the solutions of Marangoni flows due to a local source at the liquid–air interface.


Author(s):  
Johann Schröder

SynopsisThis paper provides a survey on a class of methods to obtain sufficient conditions for the inversemonotonicity of second-order differential operators. Pointwise differential inequalities as well as weak differential inequalities are treated. In particular, the theory yields results on the relation between inverse-mo no tone operators and monotone definite operators, i.e. monotone operators in the Browder–Minty sense. This presentation is restricted to ordinary differential operators. Most methods explained here can also be applied to elliptic-parabolic partial differential operators in essentially the same way.


Filomat ◽  
2002 ◽  
pp. 57-61 ◽  
Author(s):  
Raid Al-Momani ◽  
Qassem Al-Hassan ◽  
Ali Al-Jarrah ◽  
Ghanim Momani

The comparison of differential operators is a problem of the theory of partial differential operators with constant coefficients. This problem up to now doesn't have a complete solution. It was formulated in the sixties by Lars Hormander in his monograph "The Analysis of Linear Partial Differential Operators". Many facts of the theory of partial differential equations can be formulated by using the concept of pre-order relation over the set of differential operators, however it is too complicated to check the comparability condition of two differential operators. In this paper we get some sufficient conditions for the comparability of two differential operators.


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