Matches in SemOpenAlex for { <https://semopenalex.org/work/W3041270893> ?p ?o ?g. }
Showing items 1 to 86 of
86
with 100 items per page.
- W3041270893 abstract "In this thesis helical flows are investigated, in which the fluid particles simultaneously perform a rotational as well as a translational motion and, thus, move along a helix. The special feature of such flows is that they are based on a dimensional reduction, i.e. the number of coordinates, used to describe the flow is reduced. Such a reduction is referred to as dimensional reduction, since each coordinate represents one spatial dimension.The present work is divided into an analytical and a numerical part. In the analytical part, a new time-dependent coordinate system is derived from the symmetries of the incompressible Navier-Stokes equations. New conservation laws for viscous and non-viscous helical flows could be found for this coordinate system, which are shown in this thesis and have been published in the article Dierkes and Oberlack (2017). Furthermore, we consider the classical, temporally constant helical coordinate system and derive two classes of new exact solutions of the helical symmetric, full time-dependent Navier-Stokes equations. The first class of solutions is based on the symmetries of the Navier-Stokes equations and hence are denoted as invariant solutions.The second class of solutions is based on a linearization of the Navier-Stokes equations using the so-called Beltrami condition, whereby the velocity and vorticity vectors are assumed to be parallel to each other.In the numerical part of the work, a solver for the simulation of helically symmetrical flows is developed using the discontinuous Galerkin (DG) method, in which the solution is approximated by high-order polynomials. Due to the fact that helical flows in most cases are periodically in the direction of the central axis of the helix, a periodicity condition for the helical coordinates is derived. A condition for the velocity and the pressure is formulated analogously to the procedure known from the literature for axisymmetric flows (cf. Khorrami et al., 1989). This ensures the uniqueness of these physical quantities at the central axis of the helix. In addition, we introduce a suitable function space and formulate the spatial and temporal discretization of the helically symmetric Navier-Stokes equations. For the temporal discretization, we use a third order semi-explicit method in which the spatial operator is split into an explicit and an implicit part. Using this, the computational effort for transient simulations has been reduced significantly. The correct implementation is verified by various test cases including the exact solutions which have been found before. It is further shown that the convergence rates that we expect from theory are achieved. Finally, the results of direct numerical simulations at high Reynolds numbers are performed which reveal the formation of vortices, Kelvin-Helmholtz instabilities and the temporal development of energy spectra for helically invariant flows." @default.
- W3041270893 created "2020-07-16" @default.
- W3041270893 creator A5017241318 @default.
- W3041270893 date "2020-06-01" @default.
- W3041270893 modified "2023-09-25" @default.
- W3041270893 title "A high-order discontinuous Galerkin solver and exact solutions for helically invariant flows" @default.
- W3041270893 doi "https://doi.org/10.25534/tuprints-00011841" @default.
- W3041270893 hasPublicationYear "2020" @default.
- W3041270893 type Work @default.
- W3041270893 sameAs 3041270893 @default.
- W3041270893 citedByCount "0" @default.
- W3041270893 crossrefType "dissertation" @default.
- W3041270893 hasAuthorship W3041270893A5017241318 @default.
- W3041270893 hasConcept C11210021 @default.
- W3041270893 hasConcept C121332964 @default.
- W3041270893 hasConcept C126255220 @default.
- W3041270893 hasConcept C126990412 @default.
- W3041270893 hasConcept C134306372 @default.
- W3041270893 hasConcept C140820882 @default.
- W3041270893 hasConcept C158622935 @default.
- W3041270893 hasConcept C190470478 @default.
- W3041270893 hasConcept C200114574 @default.
- W3041270893 hasConcept C201076478 @default.
- W3041270893 hasConcept C2524010 @default.
- W3041270893 hasConcept C2778770139 @default.
- W3041270893 hasConcept C2781278361 @default.
- W3041270893 hasConcept C33923547 @default.
- W3041270893 hasConcept C37914503 @default.
- W3041270893 hasConcept C43058520 @default.
- W3041270893 hasConcept C53469067 @default.
- W3041270893 hasConcept C57879066 @default.
- W3041270893 hasConcept C62520636 @default.
- W3041270893 hasConcept C74650414 @default.
- W3041270893 hasConcept C80551277 @default.
- W3041270893 hasConcept C84655787 @default.
- W3041270893 hasConcept C89901390 @default.
- W3041270893 hasConceptScore W3041270893C11210021 @default.
- W3041270893 hasConceptScore W3041270893C121332964 @default.
- W3041270893 hasConceptScore W3041270893C126255220 @default.
- W3041270893 hasConceptScore W3041270893C126990412 @default.
- W3041270893 hasConceptScore W3041270893C134306372 @default.
- W3041270893 hasConceptScore W3041270893C140820882 @default.
- W3041270893 hasConceptScore W3041270893C158622935 @default.
- W3041270893 hasConceptScore W3041270893C190470478 @default.
- W3041270893 hasConceptScore W3041270893C200114574 @default.
- W3041270893 hasConceptScore W3041270893C201076478 @default.
- W3041270893 hasConceptScore W3041270893C2524010 @default.
- W3041270893 hasConceptScore W3041270893C2778770139 @default.
- W3041270893 hasConceptScore W3041270893C2781278361 @default.
- W3041270893 hasConceptScore W3041270893C33923547 @default.
- W3041270893 hasConceptScore W3041270893C37914503 @default.
- W3041270893 hasConceptScore W3041270893C43058520 @default.
- W3041270893 hasConceptScore W3041270893C53469067 @default.
- W3041270893 hasConceptScore W3041270893C57879066 @default.
- W3041270893 hasConceptScore W3041270893C62520636 @default.
- W3041270893 hasConceptScore W3041270893C74650414 @default.
- W3041270893 hasConceptScore W3041270893C80551277 @default.
- W3041270893 hasConceptScore W3041270893C84655787 @default.
- W3041270893 hasConceptScore W3041270893C89901390 @default.
- W3041270893 hasLocation W30412708931 @default.
- W3041270893 hasOpenAccess W3041270893 @default.
- W3041270893 hasPrimaryLocation W30412708931 @default.
- W3041270893 hasRelatedWork W1645260753 @default.
- W3041270893 hasRelatedWork W1842332634 @default.
- W3041270893 hasRelatedWork W1995518460 @default.
- W3041270893 hasRelatedWork W2011173199 @default.
- W3041270893 hasRelatedWork W2017172798 @default.
- W3041270893 hasRelatedWork W2017977215 @default.
- W3041270893 hasRelatedWork W2809336368 @default.
- W3041270893 hasRelatedWork W2952883520 @default.
- W3041270893 hasRelatedWork W3005670541 @default.
- W3041270893 hasRelatedWork W3008631813 @default.
- W3041270893 hasRelatedWork W3092090547 @default.
- W3041270893 hasRelatedWork W3099696062 @default.
- W3041270893 hasRelatedWork W3099822339 @default.
- W3041270893 hasRelatedWork W3100354362 @default.
- W3041270893 hasRelatedWork W3103087598 @default.
- W3041270893 hasRelatedWork W3103477234 @default.
- W3041270893 hasRelatedWork W3116858643 @default.
- W3041270893 hasRelatedWork W614616215 @default.
- W3041270893 hasRelatedWork W2183018888 @default.
- W3041270893 hasRelatedWork W2740596658 @default.
- W3041270893 isParatext "false" @default.
- W3041270893 isRetracted "false" @default.
- W3041270893 magId "3041270893" @default.
- W3041270893 workType "dissertation" @default.