A Turbulence Model for the Heat Transfer Near Stagnation Point of a Circular Cylinder

A one-equation low-Reynolds number turbulence model has been applied successfully to the flow and heat transfer over a circular cylinder in turbulent cross flow. The turbulence length-scale was found to be equal 3.7y up to a distance 0.05δ and then constant equal to 0.185δ up to the edge of the boundary layer (wherey is the distance from the surface and δ is the boundary layer thickness). The model predictions for heat transfer coefficient, skin friction factor, velocity and kinetic energy profiles were in good agreement with the data. The model was applied for Re ≤250,000 and Tu∞≤0.07

Koroner Arter Baypas Cerrahisinden Sonra Gelişen Asendan Aort Psödoanevrizması

Ascending aortic pseudoaneurysm is a rare but fatal complication of cardiac surgery. Predisposing factors associated with ascending aortic pseudoaneurysms are usually related to several factors such as infection, prior connective tissue disorders, aortic cannulation, the proximal site of graft anastomosis or the suture line of aortotomy and the aortic clamp site. We present a case of an ascending aortic pseudoaneurysm developed 7 years after coronary artery bypass grafting associated with the proximal anastomosis of a saphenous vein graft. It is essential to diagnose the aneurysm in a timely manner during follow-up, to employ effective surgical techniques and to successfully manage the patients during the perioperative and postoperative periods because rupture of the aneurysm could result in death in these patients.Asendan aort psödoanevrizması kardiyak cerrahinin nadir fakat ölümcül komplikasyonlarından biridir. Genellikle infeksiyon, önceki bağ dokusu bozuklukları, aort kanülasyonu, safen greft anastomoz proksimal bölgesi veya aortotomi sütür hattı, aortik klemp bölgesi gibi çeşitli faktörler asendan aort psödoanevrizma ile ilişkili zemin hazırlayan faktörlerdir. Biz koroner arter baypas cerrahisinden 7 yıl sonra safen ven proksimal anastomozu ile ilişkili asendan aort psödoanevrizması gelişen olguyu sunduk. Bu hastalarda anevrizma rüptürünün ölümle sonuçlanabilmesi nedeniyle takip döneminde zamanında anevrizmanın saptanması, etkili cerrahi tekniğin uygulanması ve perioperatif ve postoperatif dönemde hastaların başarılı yönetimi esastır