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Numerical Investigations of Rotating Liquids with the DLR THETA code

Munk, Johannes (2016) Numerical Investigations of Rotating Liquids with the DLR THETA code. Master's.

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Spin-up from rest (Rossby number Ro=1) for a completely fluid-filled cylinder (R = 0.707m, H = 2m) has been analysed analytically and numerically. As grounds for the analytical analysis the Wedemeyer model [38] along with its weaknesses has been investigated. It was found that contradictions exist in literature how to implement a non-linear Ekman compatibility condition. The governing partial differential equation (PDE) describing the circumferential velocity over the radius and time has been solved numerically applying MATLAB’s pdepe solver. Numerical studies applying the DLR THETA solver have been conducted for two liquids, water (1bar, 300K) and liquid hydrogen (LH2; 1bar, 22.91K). Furthermore, it has been investigated whether THETA is capable of holding an initialized rotating solution stable (initialization, Ro=0). Generally, one can conclude that a second order upwind scheme (QUDS) is more precise than a central differencing scheme (CDS), that the errors become smaller for larger dynamic viscosities ν (water always shows smaller errors than LH2) and lower rotational velocities Ω. Overall, the THETA results on the structured grids show what the analytical analysis predicts and mirror the expected physical behavior for the transients and the steady state solution good and very good, respectively. It is not clear why the computations on unstructured grids do not mirror the expected physical behavior. DLR DLR – Numerical Investigations of Rotating Liquids with

Item URL in elib:https://elib.dlr.de/109342/
Document Type:Thesis (Master's)
Title:Numerical Investigations of Rotating Liquids with the DLR THETA code
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Refereed publication:No
Open Access:No
Number of Pages:129
Keywords:rotating liquids, spin-up, Ekman compatibility condition, rigid-body motion, DLR TAU/THETA
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Raumfahrzeugsysteme - Anlagen u. Messtechnik (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Spacecraft
Deposited By: Horchler, Tim
Deposited On:16 Dec 2016 12:27
Last Modified:02 Aug 2023 15:13

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