APPLICATION OF DATA ASSIMIMILATION FOR PARAMETER CORRECTION IN SUPER CAVITY MODELLING

Authors

  • Tran Thu Ha 1/Institute of Mechanics -VAST – 264 Doi Can and 18 Hoang Quoc Viet Hanoi, Vietnam 2/University of Engineering and Technology -VNU,144 Xuan Thuy, Hanoi, Vietnam 3/ Institute of Science and Technology -VAST 18 Hoang Quoc Viet Hanoi, Vietnam
  • Nguyen Anh Son National University of Civil Engineering, 55 Giaiphong Str., Hai Ba Trung Hanoi, VietNam
  • Duong Ngoc Hai 1/Institute of Mechanics -VAST – 264 Doi Can and 18 Hoang Quoc Viet Hanoi, Vietnam 2/ University of Engineering and Technology -VNU,144 Xuan Thuy, Hanoi, Vietnam 3/Institute of Science and Technology -VAST 18 Hoang Quoc Viet Hanoi, Vietnam
  • Nguyen Hong Phong 1/Institute of Mechanics -VAST – 264 Doi Can and 18 Hoang Quoc Viet Hanoi, Vietnam 2/University of Engineering and Technology -VNU,144 Xuan Thuy, Hanoi, Vietnam

DOI:

https://doi.org/10.15625/0866-708X/54/3/6566

Keywords:

data assimilation, optimal, Runge-Kutta methods.

Abstract

On the imperfect water entry, a high speed slender body moving in the forward direction rotates inside the cavity. The super cavity model describes the very fast motion of body in water. In the super cavity model the drag coefficient plays important role in body's motion. In some references this drag coefficient is simply chosen by different values in the interval 0.8-1.0. In some other references this drag coefficient is written by the formula  with  is the cavity number,   is the angle of body axis and flow direction,  is a parameter chosen from the interval 0.6-0.85. In this paper the drag coefficient  is written with fixed  and the parameter is corrected so that the simulation body velocities are closer to observation data. To find the convenient drag coefficient the data assimilation method by differential variation is applied. In this method the observing data is used in the cost function. The data assimilation is one of the effected methods to solve the optimal problems by solving the adjoin problems and then finding the gradient of cost function.

 

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Author Biography

Tran Thu Ha, 1/Institute of Mechanics -VAST – 264 Doi Can and 18 Hoang Quoc Viet Hanoi, Vietnam 2/University of Engineering and Technology -VNU,144 Xuan Thuy, Hanoi, Vietnam 3/ Institute of Science and Technology -VAST 18 Hoang Quoc Viet Hanoi, Vietnam

Hydraulic informatic Department

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Published

2016-06-16

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Articles