Techno Press
Techno Press

Ocean Systems Engineering
  Volume 15, Number 4, December 2025 , pages 441-463
DOI: https://doi.org/10.12989/ose.2025.15.4.441
 

Design sensitivities analysis for transient incompressible laminar flows using extended complex variable method
Mojtaba Sheikhi Azqandi and Mahdi Hassanzadeh

 
Abstract
    In the present study, the extended standard complex variable method (ESCVM) was proposed as a robust method for calculating the analysis of design sensitivities, including the first and second order. The standard complex variables method (SCVM) uses only the imaginary step for sensitivity analysis. In contrast, the presented method applies both the imaginary and the real part to enhance the effectiveness of the procedure. To illustrate this, the ESCVM is employed for the transited laminar incompressible flow. The Navier-Stokes equations are solved using finite element analysis and the developed SCVM was then applied to them. It has been shown that the first order (FO) sensitivity analysis is less susceptible to variations in the step size for both the standard and extended SCVM. However, it is evident that, unlike the SCVM, the extended SCVM was less dependent on the step size in estimating the second-order sensitivity (SO). This ability can be seen as an improvement in the efficiency and robustness of the extended standard method for complex variables.
 
Key Words
    extended complex variables method; finite element analysis; incompressible laminar flows; Navier-Stokes equations; sensitivities analysis
 
Address
Mojtaba Sheikhi Azqandi: 1Mechanical Engineering Department, University of Birjand, Birjand, Iran
Mahdi Hassanzadeh: Department of Mechanical Engineering, Go.C., Islamic Azad University, Gorgan, Iran
 

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