The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomia...The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials,modified to accommodate a C~0-continuous expansion. Computationally and theoretically, by increasing the polynomial order p,high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use of the spectral/hp element method in transitional flows and ocean engineering. Finally, some of the major challenges to be overcome in order to use the spectral/hp element method in more complex science and engineering applications are discussed.展开更多
This investigation delves into the extraction dynamics of 22 per-and polyfluoroalkyl substances from PFAS contaminated firefighting materials.Two distinct test sets were executed:one contrasting a commercial product w...This investigation delves into the extraction dynamics of 22 per-and polyfluoroalkyl substances from PFAS contaminated firefighting materials.Two distinct test sets were executed:one contrasting a commercial product with water following an elaborate decontamination procedure,and the other assessing seven washing agents on materials from firefighting installations,with one agent examined at 22℃and 50℃.A general tendency for improved desorption at the higher temperature was observed.Furthermore,a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed,elucidating the role of chemical environment in the extraction process.PFAS rebound was studied for a period of up to 157 days,this unveiled a gradual escalation in PFAS22 levels,indicative of a protracted desorption mechanism.Intriguingly,PFAS with abbreviated carbon chains(C4-C6)exhibit superior desorption efficiency compared to their elongated congeners,suggesting a chain-lengthdependent decontamination potential.A comparative scrutiny between a commercially available cleaning product,featuring multiple washing and flushing steps,and a water-only treatment regimen underscores the potential efficacy of the former.This exhaustive investigation furnishes nuanced insights into PFAS extraction complexities,offering a foundation for informed decontamination strategies.展开更多
文摘The spectral/hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials,modified to accommodate a C~0-continuous expansion. Computationally and theoretically, by increasing the polynomial order p,high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use of the spectral/hp element method in transitional flows and ocean engineering. Finally, some of the major challenges to be overcome in order to use the spectral/hp element method in more complex science and engineering applications are discussed.
文摘This investigation delves into the extraction dynamics of 22 per-and polyfluoroalkyl substances from PFAS contaminated firefighting materials.Two distinct test sets were executed:one contrasting a commercial product with water following an elaborate decontamination procedure,and the other assessing seven washing agents on materials from firefighting installations,with one agent examined at 22℃and 50℃.A general tendency for improved desorption at the higher temperature was observed.Furthermore,a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed,elucidating the role of chemical environment in the extraction process.PFAS rebound was studied for a period of up to 157 days,this unveiled a gradual escalation in PFAS22 levels,indicative of a protracted desorption mechanism.Intriguingly,PFAS with abbreviated carbon chains(C4-C6)exhibit superior desorption efficiency compared to their elongated congeners,suggesting a chain-lengthdependent decontamination potential.A comparative scrutiny between a commercially available cleaning product,featuring multiple washing and flushing steps,and a water-only treatment regimen underscores the potential efficacy of the former.This exhaustive investigation furnishes nuanced insights into PFAS extraction complexities,offering a foundation for informed decontamination strategies.
