MODELING COLLISION OUTCOME IN MODERATELY DENSE SPRAYS

Luret, Gautier Menard, Thibaut Berlemont, Alain Reveillon, Julien Demoulin, Francois-Xavier Blokkeel, GregoryTo simulate primary atomization, the dense zone of sprays has to be addressed and new atomization models have been developed as the Eulerian Lagrangian spray atomization (ELSA) model [Blaisot, J. B., and Yon, I., (2005) Exp. Fluids, 39(6), pp. 977-994]. A transport equation for the liquid/gas interface density is stated and extends the concept of droplet diameter. Several related source terms require modeling attention. This work describes the contribution of collision and coalescence processes. Several questions arise: Is it possible to represent collision/coalescence from an Eulerian description of the flow? What are the key parameters? What are the particular features of collision in dense spray? To answer these questions, a Lagrangian test case, carefully resolved statistically, is used as a basis to evaluate Eulerian models. It is shown that a significant parameter is the equilibrium Weber number. If it is known, Eulerian models are able to reproduce the main features of Lagrangian simulations. To overcome the Lagrangian collision model simplification that mostly considers collisions between spherical droplets, a new test case was designed to focus on the collision process in dense spray. The numerical code, Archer, which is developed to handle interface behaviors in two-phase flow by way of direct numerical simulation (DNS) [Iyer, V, and Abraham, J., (2005), Atomization Sprays, 15(3), pp. 249-269], was used. Thanks to DNS simulations and experimental observations, the importance of nonspherical collisions is demonstrated. Despite some classical drawbacks of DNS, we observed that an equilibrium Weber number can be determined in the considered test case. This work emphasizes the ability of interface DNS simulations to describe complex turbulent two-phase flows with interfaces and to stand as a complement to new experiments

Prevalence and type of haematological malignancies among adults in a tertiary hospital in Jos-Nigeria: a sixteen-year retrospective analysis

Background: Global cancer statistics in Nigeria estimated increasing cancer occurrence per year with many unreported cases. Information regarding haematologic malignancies epidemiology in Jos is limited. This study sought to determine the prevalence, pattern and distribution of haematologic malignancies among adults in Jos, Nigeria in a 16 year period.Methods: Retrospective review of adults with haematologic malignancies diagnoses by bone marrow aspiration cytology or histology of tissue biopsies between 2000 and 2015 at the Jos University Teaching Hospital, Jos-Nigeria was conducted. Socio-demographic parameters and cytological/histologic diagnoses were extracted from the cancer register.Results: A total of 1706 cases of cancers were diagnosed during this period. Of these, 330 cases were haematologic malignancies. The prevalence of haematologic malignancies among the adult patient population was 19.3% with a male (56.7%) dominance. Leukaemia occurred the most (64.5%) followed by lymphoma (30%) and multiple myeloma (5.4%). Chronic leukaemia occurred more frequently than acute leukaemia and non-Hodgkin's lymphoma was more common than Hodgkin's lymphoma. The mean ±SD were 44±17 years for leukaemia and 43±15 years for lymphoma. The haematologic malignancies showed an increasing pattern of occurrence.Conclusion: This occurrence of haematologic malignancies among adult patients with cancer from this Centre is high. Evidence of increasing occurrence was observed. Measures targeted at improved diagnosis and care are advocated. Future studies to evaluate the genetic and environmental risk factors associated with haematologic malignancies development from this region are recommended.Keywords: Haematologic malignancies, Prevalence, Pattern, Adults, Jos, Nigeria

Potential of two-phase flows DNS to characterize interactions between turbulence and widely deformed interface

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