Research Article
ALE Numerical Simulation for a Rigid Body Rotation About a Fixed Axis in a Incompressible Viscous Fluid
Wan Il Kim,
Jae Wan Jo,
Wan Hui Jo,
Myong Chol Ri*
,
Song Bom Pyon
Issue:
Volume 11, Issue 4, December 2025
Pages:
62-75
Received:
28 June 2025
Accepted:
29 July 2025
Published:
10 October 2025
Abstract: An efficient numerical method is presented in this paper. It combines a unique ALE formulation with an adaptive time algorithm based on a Courant-Friedrichs-Levy (CFL) type condition to simulate fluid and rigid body interactions. The ALE differential formulation includes the geometric conservation law (GCL) which has the mesh velocity as a variable. In the adaptive time algorithm, the time step selection is based on the CFL type condition which is estimated by the difference between the fluid and mesh velocity. With the adaptive algorithm, the numerical simulations of incompressible viscous flow around moving bodies when the motion of the bodies is not known in advance are stable. To validate the proposed method, only the body rotation about a fixed axis in a incompressible viscous fluid is considered because it causes the large deformation of mesh. The harmonic and damped vibrations of a physical pendulum in the air are tested and the opening of a swing check valve plate is simulated to determine its local resistance characteristics in comparison with experimental data. The numerical simulations show that when a rigid body rotates in an incompressible fluid, the distortion of the mesh element is not significant and the numerical results agree with the experimental data.
Abstract: An efficient numerical method is presented in this paper. It combines a unique ALE formulation with an adaptive time algorithm based on a Courant-Friedrichs-Levy (CFL) type condition to simulate fluid and rigid body interactions. The ALE differential formulation includes the geometric conservation law (GCL) which has the mesh velocity as a variable...
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Research Article
Simulation of the Effect of Ethanol Blending Ratio on Combustion and Performance of Diesel-Ethanol Dual-Fuel Engine at Different Loads
Phyong Il Han,
Nam Su Kim,
Ri Myong Chol*,
Min Yong Jae
Issue:
Volume 11, Issue 4, December 2025
Pages:
76-87
Received:
10 July 2025
Accepted:
11 August 2025
Published:
10 October 2025
Abstract: The use of ethanol in diesel engines as an alternative to fossil fuels and air pollution prevention due to vehicle exhaust emissions has been investigated. It can be seen that for a more practical application of the performance study of diesel-ethanol dual fuel engine, the effect of ethanol on the performance at 100% load as well as at different load conditions should be considered. The effect of ethanol content on combustion and performance characteristics under different load conditions of diesel-ethanol dual-fuel engine was investigated using engine simulation tool. The engine model was constructed using the pre-combustion-diffusion combustion two phase combustion model of GT-POWER, and the simulation results of the main performance indices were compared with the test data. The effect of ethanol blending ratio on the performance of diesel-ethanol blend engine with varying ethanol content (0-20% ethanol) under different loading conditions (25-100% load) was investigated. As the load decreases, the effect of ethanol blending ratio on the brake power becomes weak. With the load decreasing to less than medium (50%), the specific fuel consumption increases rapidly. Also, the indicated thermal efficiency (ITE) and NOx emission per unit power, usually has an optimal value at medium load. It was shown that the ethanol content under different loading conditions should be set up reasonably. From the practicality and reliability of the simulation results, it is expected that the future will be used for the performance prediction and the optimal design of the diesel-ethanol dual-fuel engine at different loads using the two phase combustion model of GT-Power.
Abstract: The use of ethanol in diesel engines as an alternative to fossil fuels and air pollution prevention due to vehicle exhaust emissions has been investigated. It can be seen that for a more practical application of the performance study of diesel-ethanol dual fuel engine, the effect of ethanol on the performance at 100% load as well as at different lo...
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Research Article
Computational Analysis of Heat Transfer Enhancement in a Trapezoidal Cavity with Central Circular Obstacle
Issue:
Volume 11, Issue 4, December 2025
Pages:
88-94
Received:
15 October 2025
Accepted:
27 October 2025
Published:
3 December 2025
DOI:
10.11648/j.ijfmts.20251104.13
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Abstract: This study numerically explores natural convection in a trapezoidal enclosure with a wavy upper boundary and a centrally placed circular cavity of varying radius. The left vertical wall is maintained at a low temperature, while the right wall is heated. The remaining boundaries are adiabatic. Three obstacle sizes are considered with radius 0.05, 0.08 and 0.03 representing different levels of geometric blockage. Simulations are carried out in COMSOL Multiphysics for Rayleigh numbers between 103 and 106 under the Boussinesq approximation. Flow circulation temperature contours and heat transfer performance are analyzed for each configuration. The results indicate that enlarging the circular cavity alters the strength and structure of buoyancy-driven vortices, influencing thermal stratification and the effective heat transfer rate across the cavity. At low Rayleigh numbers conduction dominates and influence of cavity size limited whereas at higher Rayleigh numbers natural convection becomes significant and the obstacle radius strongly affects vortex dynamics and Nusselt number distribution. The findings provide insight into the coupled effect of cavity geometry and buoyancy intensity offering guidance for the design of thermal system with internal obstacles and irregular enclosures. The main objective of this paper is to find out the effect of natural convection of air within a wavy chamber using finite element methods and to investigate the influence of heated wall on free convection flow numerically.
Abstract: This study numerically explores natural convection in a trapezoidal enclosure with a wavy upper boundary and a centrally placed circular cavity of varying radius. The left vertical wall is maintained at a low temperature, while the right wall is heated. The remaining boundaries are adiabatic. Three obstacle sizes are considered with radius 0.05, 0....
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