Added Mass Of Cylinders Of Different Shapes

The exploration of added mass has become a part of fluid dynamics for more than a century,many researchers have contributed a series of basic theoretical conclusions.In this paper,several innovative experiments will be manipulated about the added mass behavior of vertical cylinders in different shapes(circular cylinder,square cylinder and rectangular plate)oscillating in still fluids(including water and paraffin oil).There are two main objectives of the study,the first is the dependence of added mass with the orientation angle of square cylinder and rectangular plate,and the second is to be the relationships between the added mass and fluid properties.The project aims at researching the added mass effect via calculating the values of dimensionless added mass coefficient C_a in two ways.One is by comparing the shifts of their natural frequencies from oscillating tests with and without liquid fluid,this method is widely accepted since its high accuracy and simple operating yet has its limitations in free decaying test.The other method of calculating C_a could be achieved by combining the instantaneous displacement and force signals captured simultaneously by laser vibrometer and load cell together yield the theory of dynamic equilibrium equation,which could reveal each value of C_a for its own single complete cycle.It can be observed that,results of C_a calculated by natural frequencies from experimental attempts of all test cylinders are obviously determined by the orientations.And the fluid density is one of the dominant parameters which could influence the added mass yet the affect from fluid viscosity is not obvious to observe.Besides,the dependence of C_a on the amplitude A/D in test fluids are mainly presented in this paper,which united two different calculations together and certified its validity by introducing fitting lines.