Dynamic simulation of mid-water trawl in fishing simulator
In order to simulate the dynamic behaviors of mid-water trawl in fishing simulator, a hydrodynamic model of mid-water trawl is established according to lumped mass model and researches on the numerical method for solving the model have also been done. In the modeling process, the mid-water trawl has been simplified by using an equivalent method, then the trawl is divided into finite mass points connected with springs without mass and fluid force of each mass point is calculated by simplifying the point to a spherical object or a rod-shaped object. To take a relative bigger step size for calculation, calculated positions of mass points instituting variables of position are used to calculate connected mass points' elastic force and every mass point's equations can be solely solved. Simulation researches of a mid-water trawl have been done, and simulated results are compared with that of flume experiments, which verifies model's rationality.
A static analysis of the tension and configuration of submerged plane nets
A non-linear finite element method is employed to determine the equilibrium configuration and tension distribution of a net set in a uniform current. The method models each mesh bar in the net as an infinitely flexible rope element connected at each end to other elements by a frictionless hinge. The Newton-Raphson method is used to solve the basic non-linear simultaneous equations with respect to tension in mesh bar and knot displacements. Global convergence to the correct solution from an initially estimated state is ensured using a loading iteration in addition to the common configuration iterative procedure in order to accurately model the shape-dependent characteristic of hydrodynamic forces. The method is shown to predict the shape and tension distribution of fishing nets with reasonable accuracy in the case examined in the present study.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.