Added mass

About: Added mass is a research topic. Over the lifetime, 2849 publications have been published within this topic receiving 47899 citations.

Mass determination with piezoelectric quartz crystal resonators

Abstract: Early investigations on quartz crystal resonators indicated, that for small mass change, the frequency shift is linearly proportional to the added mass. The accuracy of mass determination was later improved somewhat by using the so−called ’’period measurement’’ technique, which assumes a linear relationship between added mass and change in period of oscillation. However, recent studies indicate that for large mass load, the elastic properties of the deposited material have to be taken into consideration. Based on the theory of one−dimensional acoustic composite resonators, an equation relating the resonant frequency of the composite system to the mass and acoustic impedance of deposited material can be derived. The equation shows that materials with different acoustic impedances will obey different mass−frequency relations. The experimental data for a number of materials with different elastic properties are shown to be in excellent agreement with the theoretical predictions to a mass load as large as 50×...

Multi-modal Vortex-Induced Vibrations of a vertical riser pipe subject to a uniform current profile

Abstract: The transverse Vortex-Induced Vibrations of a long (length to diameter ratio, L/D=1544), flexible pipe, that was subjected to a uniform current profile (Reynolds number, Re=2.84×105) have been simulated using a strip theory Computational Fluid Dynamics model. The pipe's mass ratio (the ratio of the pipe's mass to the mass of fluid displaced by it) was varied between 1.0 and 3.0 in order to study its effect upon the vibrational behaviour of the pipe. Despite the inflow current being uniform the pipe was observed to vibrate multi-modally. Furthermore, all of the excited modes vibrated at the excitation (Strouhal) frequency. The fluid, via its added mass, was found to be able to excite modes whose natural frequencies differed from the excitation frequency. This ability was observed to decrease with increasing mass ratio.

Nonlocal frequency analysis of nanoscale biosensors

Abstract: As a first endeavor, we propose nonlocal elasticity theory for carbon nanotube based cantilever biosensors. By using the frequency-shift of the fundamental vibration mode, we develop new nonlocal frequency sensor equations utilizing energy principles. Two physically realistic configurations of the added mass, namely, point mass and distributed mass are considered. Exact closed-form expressions relating the frequency-shift and the added mass have been derived for both the cases. The proposed nonlocal sensor-equations are general in nature and depend on three non-dimensional calibration constants namely, the stiffness calibration constant, the mass calibration constant and the nonlocal calibration constant. Explicit analytical expressions of these calibration constants are derived. An example of a single wall carbon nanotube with attached multiple strands of deoxythimidine is considered to illustrate the analytical results. Molecular mechanics simulation is used to validate the new nonlocal sensor equations. The optimal values of nonlocal parameter are obtained from the molecular mechanics simulation results. The nonlocal approach generally predicts the frequency shift accurately compared to the local approach. Numerical results show the importance of considering the distributed nature of the added mass while using the nonlocal theory.

The dispersive effects of Basset history forces on particle motion in a turbulent flow

Abstract: A calculation of the asymptotic particle diffusion coefficient in an unbounded stationary homogeneous turbulent flow is performed for a particle subjected to both added mass and Basset history forces, as well as the normal Stokes drag. The original value obtained by Tchen is shown to be in error by an additional term which for a sphere of diameter d is given by (d2/2πνf)σ, νf being the kinematic viscosity, and σ the covariance of the incipient relative velocity between particle and local fluid. Noticeably this term does not depend upon the particle density. This extra term is consistent with values obtained for the particle diffusion coefficient from a numerical simulation.