Modeling of High Speed Reacting Flows: Established Practices and Future Challenges

Computational fluid dynamics (CFD) has proven to be an invaluable tool for the design and analysis of high- speed propulsion devices. Massively parallel computing, together with the maturation of robust CFD codes, has made it possible to perform simulations of complete engine flowpaths. Steady-state Reynolds-Averaged Navier-Stokes simulations are now routinely used in the scramjet engine development cycle to determine optimal fuel injector arrangements, investigate trends noted during testing, and extract various measures of engine efficiency. Unfortunately, the turbulence and combustion models used in these codes have not changed significantly over the past decade. Hence, the CFD practitioner must often rely heavily on existing measurements (at similar flow conditions) to calibrate model coefficients on a case- by-case basis. This paper provides an overview of the modeled equations typically employed by commercial- quality CFD codes for high-speed combustion applications. Careful attention is given to the approximations employed for each of the unclosed terms in the averaged equation set. The salient features (and shortcomings) of common models used to close these terms are covered in detail, and several academic efforts aimed at addressing these shortcomings are discussed

Patient information after ruptured intracranial aneurysm

Aim. This paper reports an investigation into the effects of increased information for patients treated for intracranial aneurysm rupture. Background. Intracranial aneurysm rupture is a grave condition that requires immediate care. It can be treated in two different ways, by surgery or by endovascular procedure. Intracranial aneurysm rupture can mean great changes in life, both for the patient and their spouse or relatives. Methods. An intervention study was conducted using a quasi-experimental design. Participants were recruited consecutively over a period of 12 months and consisted of 62 patients treated for intracranial aneurysm rupture at a Swedish neurosurgical clinic. They were divided into two groups: an intervention group, who received written and oral information, and a comparison group, who received only oral information. Instruments. Self-report questionnaires were sent to patients’ homes 1–3 months after the aneurysm rupture. The questionnaires consisted of one study-specific instrument with questions about understanding of the information given and the State-Trait Anxiety Inventory, which measures worry or anxiety. Findings. The intervention group considered that the information that they received was somewhat easier to understand and that it corresponded more closely to their needs, compared with the comparison group. The majority of patients in both groups expressed a need for more and improved information. Levels of anxiety were high for the majority of patients, but no significant difference was evident between groups. Furthermore, the results showed that the majority of patients were given information without their spouse or relatives being present. Conclusion. Increased information seems to be needed for these patients. There is a need to continue the work to improve information-giving to them and their relatives