Analysis of wall shear stress around a competitive swimmer using 3D Navier-Stokes equations in CFD.

This paper deals with the flow dynamics around a competitive swimmer during underwater glide phases occurring at the start and at every turn. The influence of the head position, namely lifted up, aligned and lowered, on the wall shear stress and the static pressure distributions is analyzed. The problem is considered as 3D and in steady hydrodynamic state. Three velocities (1.4 m/s, 2.2 m/s and 3.1 m/s) that correspond to inter-regional, national and international swimming levels are studied. The flow around the swimmer is assumed turbulent. The Reynolds-averaged Navier-Stokes (RANS) equations are solved with the standard k-ω turbulent model by using the CFD (computational fluid dynamics) numerical method based on a volume control approach. Numerical simulations are carried out with the ANSYS FLUENT® CFD code. The results show that the wall shear stress increases with the velocity and consequently the drag force opposing the movement of the swimmer increases as well. Also, high wall shear stresses are observed in the areas where the body shape, globally rigid in form, presents complex surface geometries such as the head, shoulders, buttocks, heel and chest.

Upper eyelid orbicularis oculi flap with tarsoconjunctival island for reconstruction of full-thickness lower lid defects.

The reconstruction of full-thickness defects of the lower eyelid after tumor resection is a challenging operation. The great number of techniques for these defects shows that none of them is the operation of choice. The method of reconstruction will be chosen according to the extent of the defect, the missing components of the eyelid structure, the age of the patient, and the quantity and the quality of the surrounding tissues. In this article, we propose, under specific indications, the use of a pedicled myocutaneous orbicularis oculi flap with a tarsoconjunctival island from the upper eyelid to reconstruct full-thickness lower lid defects. The more choices in a surgeon's armamentarium, the more easily the difficult problems of periorbital surgical oncology will be resolved.

Island mucochrondrocutaneous flap for reconstruction of total loss of the lower eyelid.

The methods usually employed for reconstruction of total lower eyelid loss include (1) tarsoconjunctival flaps from the upper eyelid and skin-graft cover and (2) chondromucosal grafts and local skin-flap cover. We report a technique for coverage of these defects with an island flap involving the full thickness of the ipsilateral nasal wall based on the dorsal (external) nasal vessels, terminal branches of the ophthalmic vessels. The advantages of this method are (1) the main components of the eyelid (skin, tarsus, conjunctiva) are reconstructed in a single short operation, even under local anesthesia, (2) there is one donor area that can be closed primarily without significant deformity, (3) the upper lid remains intact, and ectropion is improbable, and (4) the procedure involves a short hospitalization. As disadvantages we might mention bulkiness of the new eyelid and difficult dissection of the (subcutaneous) pedicle.