Johny Martinez - Academia.edu (original) (raw)

Papers by Johny Martinez

Research paper thumbnail of A chebyshev collocation spectral method for numerical simulation of incompressible flow problems

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2007

This paper concerns the numerical simulation of internal recirculating flows encompassing a two-d... more This paper concerns the numerical simulation of internal recirculating flows encompassing a two-dimensional viscous incompressible flow generated inside a regularized square driven cavity and over a backward-facing step. For this purpose, the simulation is performed by using the projection method combined with a Chebyshev collocation spectral method. The incompressible Navier-Stokes equations are formulated in terms of the primitive variables, velocity and pressure. The time integration of the spectrally discretized, incompressible Navier-Stokes equations is performed by a secondorder mixed explicit/implicit time integration scheme. This scheme is a combination of the Crank-Nicolson scheme operating on the diffusive terms and a second-order Adams-Bashforth scheme acting on the advective terms. The projection method is used to split the solution of the incompressible Navier-Stokes equations in two decoupled problems: the Burgers equation to predict an intermediate velocity field and the Poisson equation for the pressure, which is used to correct the intermediate velocity field and satisfy the continuity equation. Numerical simulations for flows inside a two-dimensional regularized square driven cavity for Reynolds numbers up to 10000 and over a backward-facing step for Reynolds numbers up to 875 are presented and compared with numerical results previously published, where good agreement is demonstrated.

Research paper thumbnail of Density of liquid thallium

Metallurgical Transactions, 1973

... of Metals, London, 1969. 9. DA Karlyn, JW Cahn, and M. Cohen: Trans. TMS-AIME, 1969, vol. 245... more ... of Metals, London, 1969. 9. DA Karlyn, JW Cahn, and M. Cohen: Trans. TMS-AIME, 1969, vol. 245, p. 197. Density of Liquid Thallium JOHNNY MARTINEZ AND HUGH A. WALLS WHITE x and Lucas have discussed alternative tech-niques for measuring liquid metal density. ...

Research paper thumbnail of A modeling study of the coastal eastern boundary current system off Iberia and Morocco

Journal of Geophysical Research: Oceans, 2000

To investigate the northern Canary Current system (NCCS), results from four numerical experiments... more To investigate the northern Canary Current system (NCCS), results from four numerical experiments of increasing complexity are examined. Experiment 1, which uses seasonal wind forcing only, shows that as expected, wind forcing is the key generative mechanism for the current, upwelling, meander, eddy, and filament structures. Experiments 2 and 3, which have the additional effects of irregular coastline geometry, show the following: capes are areas for enhanced upwelling, extensive filaments, maximum current velocities, and enhanced growth of cyclonic meanders and eddies; an embayment like the Gulf of Cadiz is a primary region for anticyclonic meander and eddy development. The results from the complex flow regime of Experiment 4, which has the additional effects of thermohaline gradients and Mediterranean Outflow, highlights the major characteristics and unique features (such as the generation of Meddles) of the NCCS with relatively close similarities to field observations.

Research paper thumbnail of A chebyshev collocation spectral method for numerical simulation of incompressible flow problems

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2007

This paper concerns the numerical simulation of internal recirculating flows encompassing a two-d... more This paper concerns the numerical simulation of internal recirculating flows encompassing a two-dimensional viscous incompressible flow generated inside a regularized square driven cavity and over a backward-facing step. For this purpose, the simulation is performed by using the projection method combined with a Chebyshev collocation spectral method. The incompressible Navier-Stokes equations are formulated in terms of the primitive variables, velocity and pressure. The time integration of the spectrally discretized, incompressible Navier-Stokes equations is performed by a secondorder mixed explicit/implicit time integration scheme. This scheme is a combination of the Crank-Nicolson scheme operating on the diffusive terms and a second-order Adams-Bashforth scheme acting on the advective terms. The projection method is used to split the solution of the incompressible Navier-Stokes equations in two decoupled problems: the Burgers equation to predict an intermediate velocity field and the Poisson equation for the pressure, which is used to correct the intermediate velocity field and satisfy the continuity equation. Numerical simulations for flows inside a two-dimensional regularized square driven cavity for Reynolds numbers up to 10000 and over a backward-facing step for Reynolds numbers up to 875 are presented and compared with numerical results previously published, where good agreement is demonstrated.

Research paper thumbnail of Density of liquid thallium

Metallurgical Transactions, 1973

... of Metals, London, 1969. 9. DA Karlyn, JW Cahn, and M. Cohen: Trans. TMS-AIME, 1969, vol. 245... more ... of Metals, London, 1969. 9. DA Karlyn, JW Cahn, and M. Cohen: Trans. TMS-AIME, 1969, vol. 245, p. 197. Density of Liquid Thallium JOHNNY MARTINEZ AND HUGH A. WALLS WHITE x and Lucas have discussed alternative tech-niques for measuring liquid metal density. ...

Research paper thumbnail of A modeling study of the coastal eastern boundary current system off Iberia and Morocco

Journal of Geophysical Research: Oceans, 2000

To investigate the northern Canary Current system (NCCS), results from four numerical experiments... more To investigate the northern Canary Current system (NCCS), results from four numerical experiments of increasing complexity are examined. Experiment 1, which uses seasonal wind forcing only, shows that as expected, wind forcing is the key generative mechanism for the current, upwelling, meander, eddy, and filament structures. Experiments 2 and 3, which have the additional effects of irregular coastline geometry, show the following: capes are areas for enhanced upwelling, extensive filaments, maximum current velocities, and enhanced growth of cyclonic meanders and eddies; an embayment like the Gulf of Cadiz is a primary region for anticyclonic meander and eddy development. The results from the complex flow regime of Experiment 4, which has the additional effects of thermohaline gradients and Mediterranean Outflow, highlights the major characteristics and unique features (such as the generation of Meddles) of the NCCS with relatively close similarities to field observations.