1,736 research outputs found

    An objective perspective for classic flow classification criteria

    Get PDF
    Four classic criteria used to the classification of complex flows are discussed here. These criteria are useful to identify regions of the flow related to shear, elongation or rigid-body motion. These usual criteria, namely QQ, Δ\Delta, λ2\lambda_{2} and λcr/λci\lambda_{cr}/\lambda_{ci}, use the fluid's rate-of-rotation tensor, which is known to vary with respect to a reference frame. The advantages of using objective (invariant with respect to a general transformation on the reference frame) criteria are discussed in the present work. In this connection, we construct versions of classic criteria replacing standard vorticity, a non-objective quantity, by effective vorticity, a rate of rotation tensor with respect to the angular velocity of the eigenvectors of the strain rate tensor. The classic criteria and their corresponding objective versions are applied to classify two complex flows: the transient ABC flow and the flow through the abrupt 4:1 contraction. It is shown that the objective versions of the criteria provide richer information on the kinematics of the flowComment: 11 pages, 4 figures (minor corrections and improvements

    Advances in the Analysis and Prediction of Turbulent Viscoelastic Flows

    Get PDF
    It has been well-known for over six decades that the addition of minute amounts of long polymer chains to organic solvents, or water, can lead to significant turbulent drag reduction. This discovery has had many practical applications such as in pipeline fluid transport, oil well operations, vehicle design and submersible vehicle projectiles, and more recently arteriosclerosis treatment. However, it has only been the last twenty-five years that the full utilization of direct numerical simulation of such turbulent viscoelastic flows has been achieved. The unique characteristics of viscoelastic fluid flow are dictated by the nonlinear differential relationship between the flow strain rate field and the extra-stress induced by the additive polymer. A primary motivation for the analysis of these turbulent fluid flows is the understanding of the effect on the dynamic transfer of energy in the turbulent flow due to the presence of the extra-stress field induced by the presence of the viscoelastic polymer chain. Such analyses now utilize direct numerical simulation data of fully developed channel flow for the FENE-P (Finite Extendable Nonlinear Elastic - Peterlin) fluid model. Such multi-scale dynamics suggests an analysis of the transfer of energy between the various component motions that include the turbulent kinetic energy, and the mean polymeric and elastic potential energies. It is shown that the primary effect of the interaction between the turbulent and polymeric fields is to transfer energy from the turbulence to the polymer

    Leveraging the COVID-19 fermentation trend to enhance nutrition and food safety Extension efforts

    Get PDF
    Our program aimed to increase knowledge related to fermented foods. Over 400 stakeholders registered for a webinar series that focused on defining fermented foods, health benefits of fermenting foods, and the safety of fermented foods. Participants indicated increases in knowledge and overall satisfaction with the content of the fermentation curriculum. The impact of the COVID-19 pandemic on the program outcomes are discussed

    Determination of Gluten Peptides Associated with Celiac Disease by Mass Spectrometry

    Get PDF
    Gluten is a big protein network composed of monomeric fraction (prolamins) and polymeric fraction (glutelins), occurring in many cereal-based products, especially in those containing wheat. Gluten peptides can trigger food allergies and intolerances, including inflammatory reactions as the celiac disease, an autoimmune disorder of the small intestine characterized by mucosal degeneration and villous atrophy. The treatment is the permanent exclusion of gluten from diet. However, gluten analysis is a very difficult task, due to the high complexity of polypeptides and the lack of consensus on the most appropriate analytical method. Proteomics approaches, combining liquid chromatography and mass spectrometry in tandem (LC-MS/MS), have been pointed as the most promising non-immunological techniques for gluten detection. LC-MS analyses associated with bioinformatics and specific-prolamin database can solve methodological limitations since it is based on the accurate molecular mass of peptide biomarkers. One of the major contributions of proteomics has been the identification of epitopes of gluten peptides responsible for wheat-related diseases. Recent works have defined grain-specific gluten peptides and also the lowest concentration at which peptides could be confidently detected. Proteomic application for gluten quantification should support not only regulatory limits in processed foods, but also the safety of consumers about food labeled as gluten-free

    Temporomandibular joint prostheses: An alternative for impacted mandibular condyle in middle cranial fossa

    Get PDF
    AbstractThe dislocation of the mandibular condyle in the middle cranial fossa is a rare condition with few reports in the literature. The authors described the first case reported of unilateral dislocation and fracture treated and reconstructed with a Temporo mandibular joint prostheses. Pre-surgical conduct, medical positions of the Neurosurgery, Radiology and Oral and Maxillofacial teams are described. Also, two years post-operative evaluations are detailed, including information regarding maximum interincisal opening, function, speech, pain and diet of the patient

    Using Rapidity Gaps to Distinguish Between Higgs Production by W and Gluon Fusion

    Get PDF
    The possibility of distinguishing between two higgs production mechanisms, W fusion and gluon fusion, is investigated using the Monte Carlo event generator PYTHIA. It is shown that, considering the designed CM energy and luminosity for the LHC, it is not possible to distinguish between the two higgs production processes as, for a given integrated luminosity, they lead to the same number of events containing a rapidity gap.Comment: uudecoded compressed tar file containing a tex file and 6 figure files. Two more figures, avaiable from the authors upon reques
    corecore