Puangkird, Bumroong

Loading...
Thumbnail Image
Preferred name
Puangkird, Bumroong
Alternative Name
Puangkird, B.
Main Affiliation
Email
bumroong.pu@kmitl.ac.th

Settings

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.