NUMERICAL ANALYSIS OF THE FLOW OF A 2-D JETS UNDER VARIABLE NOISE

Resumo

The present paper shows an physical analysis for bidimensional fluid flow evolutions of a
submerged rectangular free jet at low Reynolds Number. The flows were simulated using a code based
on the Fourier Pseudospectral Method coupled with immersed boundary method (IBM) IMERSPEC2D
(Mariano [1]), which uses the Fast Fourier Transform (FFT) to solve the bi dimensional Navier-Stokes
equations; the jet profile was implemented using the multidirect-forcing method, and the Runge-Kutta
4th order method with 6 steps (RK46) was used temporal method. The aims of this paper is validate
of noise required (0%, 1% and 3% of noise) to simulate the jet flows to Re = 100, at five different
mesh: 64x16, 128x32, 256x64, 512x128 and 1024x256. The results presented in this paper are based in
the velocity profile at five positions: vertical profile at position 12D, 16D, 32D and 64D, where D is the
diameter of the jet. A preferential mesh of 256 x 64 is chosen according to its accuracy and computational
cost, however when the noise was being analyzed, the mesh was considered inadequate due to its low
precision and the already existing numerical noise in its structure.