Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modal analysis of a spinning disk in a dense fluid as a model for high
  head hydraulic turbines   In high head Francis turbines and pump-turbines in particular, Rotor Stator
Interaction (RSI) is an unavoidable source of excitation that needs to be
predicted accurately. Precise knowledge of turbine dynamic characteristics,
notably the variation of the rotor natural frequencies with rotation speed and
added mass of the surrounding water, is essential to assess potential resonance
and resulting amplification of vibrations. In these machines, the disk-like
structures of the runner crown and band as well as the head cover and bottom
ring give rise to the emergence of diametrical modes and a mode split
phenomenon for which no efficient prediction method exists to date. Fully
coupled Fluid-Structure Interaction (FSI) methods are too computationally
expensive; hence, we seek a simplified modelling tool for the design and the
expected-life prediction of these turbines. We present the development of both
an analytical modal analysis based on the assumed mode approach and potential
flow theory, and a modal force Computational Fluid Dynamics (CFD) approach for
rotating disks in dense fluid. Both methods accurately predict the natural
frequency split as well as the natural frequency drift within 7.9% of the
values measured experimentally. The analytical model explains how mode split
and drift are respectively caused by linear and quadratic dependence of the
added mass with relative circumferential velocity between flexural waves and
fluid rotation.

34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat