Shahrood University of Technology Journal of Solid and Fluid Mechanics 2251-9475 10 4 2020 12 21 Numerical investigation of sensitivity of AUV dynamic coefficients and added mass to variations in amplitude and frequency of excitation Numerical investigation of sensitivity of AUV dynamic coefficients and added mass to variations in amplitude and frequency of excitation 195 208 2000 10.22044/jsfm.2020.7530.2728 FA H. Adnian Arani shahid rajaee teacher training university tehran M. Mahdi Mech. Eng., shahid rajaee Univ., Tehran, Iran M. Varmazyar shahid rajaee teacher training Tehran Journal Article 2018 10 07 The hydrodynamic coefficients and derivatives of a AUV are very important parameters that affect its control and maneuverability. Usually, a straight-line towing test method and forced heave and pitch motion are used to derive coefficients. In this paper, we used the CFD method with the control volume approach and commercial Fluent software, the flow is simulated around a subsurface. First, simulation was performed for straight-line towing test to by comparing the results with experimental results, to selected the grid type and suitable turbulent model. To simulate forced heave and pitch motion, a udf program is written that oscillates the model with specific amplitudes and frequencies. Software output is the time-coefficients varying that is converted to dynamic coefficients by a Matlab program. The results show that the Z_W ̇^' coefficient is approximately constant with variation of amplitude and oscillation frequency of the model but the Z_W^', M_W^' and M_W ̇^' coefficients change with frequency and amplitude to 35%. The results show all coefficients of pitch motion increased with increasing amplitude and frequency of model oscillation that the lowest increase is related to the M_q ̇^' coefficient with less than 8% variation in its absolute value. The remaining coefficients showed up to 80%. The hydrodynamic coefficients and derivatives of a AUV are very important parameters that affect its control and maneuverability. Usually, a straight-line towing test method and forced heave and pitch motion are used to derive coefficients. In this paper, we used the CFD method with the control volume approach and commercial Fluent software, the flow is simulated around a subsurface. First, simulation was performed for straight-line towing test to by comparing the results with experimental results, to selected the grid type and suitable turbulent model. To simulate forced heave and pitch motion, a udf program is written that oscillates the model with specific amplitudes and frequencies. Software output is the time-coefficients varying that is converted to dynamic coefficients by a Matlab program. The results show that the Z_W ̇^' coefficient is approximately constant with variation of amplitude and oscillation frequency of the model but the Z_W^', M_W^' and M_W ̇^' coefficients change with frequency and amplitude to 35%. The results show all coefficients of pitch motion increased with increasing amplitude and frequency of model oscillation that the lowest increase is related to the M_q ̇^' coefficient with less than 8% variation in its absolute value. The remaining coefficients showed up to 80%. https://jsfm.shahroodut.ac.ir/article_2000_76c1fca2ef7ee8d8e56e01014e4cc551.pdf