Seminar khoa học chủ đề: Advanced Numerical Methods for Fluid Flow and Structural Analysis

Vào 14h00, ngày 11/09/2026, Viện IAST tổ chức buổi trao đổi học thuật tại Phòng họp khán đài A - VP Tân Hưng với nội dung chi tiết như sau:

1/  NCS. Phan Thị Diệu Thúy

Tên báo cáo: Permeability effect on the characteristics of flow past porous circular cylinder located near a moving wall.
Tóm tắt: This numerical study investigates the unsteady flow past a permeable circular cylinder located near a moving wall. The simulations cover a wide range of porosity (𝜀 = 10⁻⁴ – 0.8) and gap ratios (𝐺∕𝐷 = 0.6–5). The Reynolds number is fixed at 𝑅𝑒 = 150 to examine near-wall dynamics, while a range of 𝑅𝑒 = 40 – 400 is considered for the isolated cylinder case. Four distinct flow regimes are identified: overshoot (OS), overshoot with wavy vortex street (PW), primary and meandering vortex street (PM), and co-shedding vortex street (OP). At small gap ratios (𝐺∕𝐷 < 0.6), the transition from the PW to the OS regime occurs at a critical porosity of 𝜀 = 0.4, indicating the role of permeability in stabilizing the shear layers. For intermediate gaps (0.6 ≤ 𝐺∕𝐷 ≤ 3), the OP regime is observed only when 𝜀 > 0.6 due to significant flow penetration. Regarding hydrodynamic forces, the wall effect significantly reduces lift coefficient fluctuations for 𝐺∕𝐷 < 1.8. A decrease in porosity leads to an increase in stagnation pressure, where stagnation points shift toward the moving wall at small gaps (𝐺∕𝐷 ≤ 1.2) but approach those of a rigid cylinder at larger gaps. Furthermore, high porosity (𝜀 > 0.6) suppresses mean lift generation (𝐶𝐿 ≈ 0) regardless of the gap ratio, while the time-averaged drag coefficient reaches a maximum of 1.71 at large gap ratios (𝐺∕𝐷 > 4). These findings provide criteria for flow control in engineering applications, particularly for mitigating vortex-induced vibrations in subsea pipelines and enhancing thermal efficiency in heat exchangers.

2/  NCS. Vũ Đông Dương

Tên báo cáo: A moving kriging meshfree formulation based on higher-order shear deformation theory for plate structures
Tóm tắt: 

This report presents the Moving Kriging Meshfree method (MKM) combined with Higher-order Shear Deformation Theory (HSDT) for analyzing the mechanical behavior of plate structures. The computational domain is discretized using an arbitrarily distributed set of nodes, and each evaluation point is approximated through a support domain determined from its neighboring nodes, enabling flexible treatment of problems involving complex geometries and multi-field coupling without requiring mesh generation. The MKM shape functions are constructed based on a polynomial basis and a Gaussian correlation function. By applying the virtual work principle, the weak form of the governing equations is established, from which the global stiffness matrix and mass matrix are assembled. Owing to the Kronecker-delta property of the MKM shape functions, Dirichlet boundary conditions can be imposed directly, a distinctive advantage over other meshfree methods. The report addresses both the static problem and the eigenvalue problem, which serve for free vibration analysis and buckling analysis of plate structures. In addition, several directions for improving the method are discussed, including the use of Chebyshev and Legendre orthogonal polynomials to overcome the ill-conditioning of the correlation matrix. The results demonstrate that the MKM combined with HSDT is a numerical tool of high accuracy, stability, and flexibility for analyzing advanced plate structures such as functionally graded plates and piezoelectric–magnetoelectric plates.

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