Puangkird, Bumroong

Preferred name

Puangkird, Bumroong

Alternative Name

Puangkird, B.

Main Affiliation

School of Engineering

bumroong.pu@kmitl.ac.th

Now showing 1 - 5 of 5

Some of the metrics are blocked by your
consent settings
A design of silicon-based racetrack microcavity resonator using FDTD
(2002-12-01)
Somkuarnpanit, S.
;
Puangkird, B.
;
Koosirivanichakorn, P.
This paper proposes a design of the racetrack microcavity resonator based on silicon substrate. The optimized dimensions of the structure were found by FDTD simulation. The characteristics were also found by the method, and further compared with another model of mode coupling theory. The optimized dimensions of straight guide at wavelength 1.55 μm are thickness and width of 0.4 μm. The curve guide provides the maximum at 1μm whereas the resonating section requires small coupling section of about 3 μm.
Some of the metrics are blocked by your
consent settings
Alternative subcell discretisations for viscoelastic flow: Stress interpolation
(2007-10-25)
Belblidia, F.
;
Matallah, H.
;
Puangkird, B.
;
Webster, M. F.
This study is concerned with the investigation of the associated properties of subcell discretisations for viscoelastic flows, where aspects of compatibility of solution function spaces are paramount. We introduce one new scheme, through a subcell finite element approximation fe(sc), and compare and contrast this against two precursor schemes-one with finite element discretisation in common, but at the parent element level quad-fe; the other, at the subcell level appealing to hybrid finite element/finite volume discretisation fe/fv(sc). To conduct our comparative study, we consider Oldroyd modelling and two classical steady benchmark flow problems to assess issues of numerical accuracy and stability-cavity flow and contraction flow. We are able to point to specific advantages of the finite element subcell discretisation and appreciate the characteristic properties of each discretisation, by analysing stress and flow field structure up to critical states of Weissenberg number. Findings reveal that the subcell linear approximation for stress within the constitutive equation (either fe or fv) yields a more stable scheme, than that for its quadratic counterpart (quad-fe), whilst still maintaining second-third order accuracy. The more compatible form of stress interpolation within the momentum equation is found to be via the subcell elements under fe(sc); yet, this makes no difference under fe/fv(sc). Furthermore, improvements in solution representation are gathered through enhanced upwinding forms, which may be coupled to stability gains with strain-rate stabilisation. © 2007 Elsevier B.V. All rights reserved.
Some of the metrics are blocked by your
consent settings
Numerical simulation of viscoelastic fluids in cross-slot devices
(2009-10-01)
Puangkird, B.
;
Belblidia, F.
;
Webster, M. F.
Cross-slot flow for viscoelastic fluids is investigated through various numerical algorithms, demonstrating the effectiveness of such devices to study constitutive models and their resulting rheological properties. Here, the steady problem manifests the long-time exposure to significant extension. Solutions are compared and contrasted for a range of rheological models of varying shear and extensional response, including phenomenologically based models from network-theory of Oldroyd/Phan-Thien-Tanner class, and also kinetic-theory based forms of FENE-CR and pom-pom. Matching rheological fluid characteristics are sought across various models through peak extensional viscosity and Trouton ratio. Using the Oldroyd-B model and for the more solvent-dominated fluid, deformation rate peak-levels are practically unaffected by rise in elasticity. Alternatively, for the more polymeric-based fluid, such peak-levels are reduced with increasing elasticity. Successful attempts have been made to match rheological response and complex flow fields between strain hardening polymeric-based Oldroyd-B and constant shear viscosity FENE-CR models, so that the two fluids display the closest cross-slot flow field features. Here, similar stress field contours are observed for both models over a range of elasticity levels, with comparable pressure-drops. Similarly, strain hardening and strain softening e-PTT models are rheologically matched to SXPP models, which also provide insight into the distribution of molecular backbone-stretch. From the combination of viscometric data and numerical solutions for cross-slot flow, local peaks may be derived in strain-rate and maximum levels of normal stress may be accurately predicted with these models. This demonstrates a significant shift towards qualitative agreement with corresponding experimental findings. © 2009 Elsevier B.V. All rights reserved.
Some of the metrics are blocked by your
consent settings
NUMERICAL STUDY AND DESIGN OF SIDE-DIFFUSERS FOR FORMULA-SAE CAR
(2022-03-31)
Chatpattanasiri, C.
;
Bunpapong, K.
;
Sahastharachai, M.
;
Puangkird, B.
This research focuses on designing side-diffusers for Formula Student race car. The aim is to reduce the lap time in a circular track called Skid-pad event by mean of increasing downforce generated by the diffusers, a ground effect aerodynamic device. Utilizing three-dimensional CFD simulation via cloud computing to obtain the most optimal design among the studied parameters. The study employs SST k-omega turbulence model with an incompressible flow and isothermal assumptions and the CFD model is validated via wind tunnel testing. Finally, the results show that the optimal outlet angle of 32 degrees due to the behavior vortex above the diffuser and the higher the outlet to inlet height, the lesser downforce.
Some of the metrics are blocked by your
consent settings
Generalised approach for transient computation of start-up pressure-driven viscoelastic flow
(2008-05-16)
Keshtiban, I. J.
;
Puangkird, B.
;
Tamaddon-Jahromi, H.
;
Webster, M. F.
This article investigates a generalised solution approach for transient viscoelastic flows employing consistent dynamic boundary conditions. Such a procedure vaunts three key properties-independence of reference frame, problem dimension and constitutive equation type. Three different boundary condition protocols have been investigated, two transient and one steady, through a time-dependent incremental pressure-correction formulation with a hybrid finite element/finite volume scheme. These procedures are compared and contrasted through application to pressure-driven start-up flow in 4:1 planar rounded-corner contractions for two fluid models, Oldroyd and pom-pom. Some novel differences are highlighted in the dynamic evolution of flow structure and the impact upon stress generation, as a consequence of protocol, whether steady or transient, under flow-rate or force-driven control. Overshoot-undershoot kinematics observed under any particular flow protocol have been mutually linked to the precise boundary conditions imposed. Under flow-rate controlled protocols, large oscillations are stimulated in pressure, which may disturb computational tractability. Comparatively, the evolution of force-driven flow can provide considerably smoother development patterns in pressure, with largest attached vortices and strong oscillatory vortex structure features. Specifically under transient flow-rate control, some distinct complex flow features have emerged, including reversed flow, followed by vortex detachment and reattachment. For pom-pom SXPP-fluids and force-driven protocol, transient flow development is observed to be relatively smooth and non-oscillatory at a Weissenburg number of unity. At larger levels of Weissenburg number, transient overshoots have been detected in characteristic variables of stress and molecular backbone-stretch. In addition, Weissenburg number continuation to steady state, has been shown to disconnect the dynamics between velocity and stress, which prevents highly elastic localised regions from developing. © 2008 Elsevier B.V. All rights reserved.

Puangkird, Bumroong

Filters

Settings

Sort By

Results per page