Evaluation of a near-wall-modeled large eddy lattice boltzmann method for the analysis of complex flows relevant to IC engines

In this paper, we compare the capabilities of two open source near-wall-modeled large eddy simulation (NWM-LES) approaches regarding prediction accuracy, computational costs and ease of use to predict complex turbulent flows relevant to internal combustion (IC) engines. The applied open source tools are the commonly used OpenFOAM, based on the finite volume method (FVM), and OpenLB, an implementation of the lattice Boltzmann method (LBM). The near-wall region is modeled by the Musker equation coupled to a van Driest damped Smagorinsky-Lilly sub-grid scale model to decrease the required mesh resolution. The results of both frameworks are compared to a stationary engine flow bench experiment by means of particle image velocimetry (PIV). The validation covers a detailed error analysis using time-averaged and root mean square (RMS) velocity fields. Grid studies are performed to examine the performance of the two solvers. In addition, the differences in the processes of grid generation are highlighted. The performance results show that the OpenLB approach is on average 32 times faster than the OpenFOAM implementation for the tested configurations. This indicates the potential of LBM for the simulation of IC engine-relevant complex turbulent flows using NWM-LES with computationally economic costs

DNA extraction from human saliva deposited on skin and its use in forensic identification procedures Extração de DNA de saliva humana depositada sobre a pele e sua aplicabilidade aos processos de identificação forense

Saliva is usually deposited in bite marks found in many homicides, assault and other criminal cases. In the present study, saliva obtained from volunteers was deposited on skin and recovered for DNA extraction and typing in order to evaluate its usefulness for practical case investigation and discuss the contribution of forensic dentistry to saliva DNA typing. Twenty saliva samples were colleted from different donors and used as suspects' samples. Five of these samples were randomly selected and deposited (250 µl) on arm skin. Saliva was collected from skin using the double swab technique. DNA from saliva and skin-deposited saliva samples was extracted by the phenol-chloroform method. DNA samples were amplified by PCR for DNA typing using a set of 15 STRs. The recovery of DNA from saliva deposited in the skin was 14 to 10 times lower than DNA quantity from saliva samples. DNA typing was demonstrated in 4 of 5 deposited saliva samples, the likelihood ratios estimated for these samples based on data of the Brazilian population were 1:11, 1:500, 1:159.140 and 1:153.700.123. Our results indicate that standardized procedures used for DNA collection and extraction from skin-deposited saliva can be used as a method to recover salivary DNA in criminal cases. However, it is important to observe that DNA recovery in forensic samples can be difficult. This study suggests that the analysis of saliva deposited on skin be incorporated into a criminal investigation since it may have great discriminatory power.<br>A saliva é usualmente depositada em marcas de mordida encontradas em homicídios, agressões e outros crimes. Neste estudo, a saliva obtida de voluntários foi depositada na pele, recuperada para extração e tipagem do DNA, para avaliação de sua utilização e sua contribuição na odontologia legal. Vinte amostras de saliva foram coletadas de diferentes doadores e utilizadas como amostras de suspeitos. Cinco dessas amostras foram sorteadas e depositadas (250 µl) na pele. A saliva foi coletada da pele usando-se a técnica do duplo esfregaço. O DNA da saliva e das amostras de saliva depositadas sobre a pele foi extraído pelo método fenol-clorofórmio. As amostras de DNA foram amplificadas por PCR para a tipagem do DNA usando-se um grupo de 15 STRs. O DNA recuperado da saliva depositada na pele foi de 14 a 10 vezes menor que o DNA das 20 amostras de saliva. O perfil do DNA foi demonstrado em 4 de 5 amostras de saliva depositadas, e a razão de verossimilhança das amostras baseada em dados da população brasileira foi 1:11, 1:500, 1:159,140 e 1:153,700,123. Nossos resultados indicam que procedimentos padronizados utilizados para coleta e extração de DNA de saliva depositada podem ser utilizados como um método para recuperar DNA de saliva em casos forenses; entretanto, é importante observar que amostras forenses podem apresentar problemas na recuperação do DNA em quantidades adequadas. Este estudo sugere que a análise de saliva depositada sobre a pele pode ser incorporada ao conjunto de provas de um inquérito criminal já que possui um grande poder discriminatório