Unsteady boundary layer flow and heat transfer over a stretching sheet: heat flux case

Unsteady two-dimensional boundary layer flow and heat transfer over a stretching flat plate in a viscous and incompressible fluid of uniform ambient temperature is investigated in this paper. It is assumed that the velocity of the stretching sheet and the heat flux from the surface of the plate vary inverse proportionally with time. Two equal and opposite forces are impulsively applied along the plate so that the plate is stretched keeping the origin fixed. Using appropriate similarity variables, the basic partial differential equations are transformed into a set of two ordinary differential equations. These equations are solved numerically for some values of the governing parameters using the Runge-Kutta method of fourth order. Flow and heat transfer characteristics are determined and represented in some tables and figures. It is found that the structure of the boundary layer depends on the ratio of the velocity of the potential flow near the stagnation point to that of the velocity of the stretching surface. In addition, it is shown that the heat transfer from the plate increases when the Prandtl number increases. The present results include also the steady situation as a special case considered by other authors. Comparison with known results is very good

Effect of the magnetic field and heat generation on the free convection flow in a tall cavity filled with a porous medium

An analytical study of the steady magnetohydrodynamics (MHD) free convection in an tall cavity filled with a fluid-saturated porous medium and with internal heat generation has been performed. It is considered that the Darcy law model is used. It is assumed that a uniform magnetic field normal to the walls of the cavity is externally imposed. The values of the governing parameters are as follows: Hartmann number $\operatorname{Ha}=0, 10$ and $50$, Rayleigh number $\operatorname{Ra} = 10^{3}$, and the aspect ratio $a=0.01$. The velocity and temperature profile are determined. These profiles are presented graphically at the center line of the cavity. It is found that the analytical solution is in very good agreement with the numerical solution which is obtained by solving partial differential equations using a finite-difference method

Intake of Plant Based Foods and Colorectal Cancer. A Case-Control Study in Romania

Colorectal cancer (CRC) represents the third most common type of cancer worldwide with high incidence rates in our country as well. Both dietary habits and lifestyle factors have a strong contribution in preventing colorectal cancer. A healthy dietary pattern based on adequate intake of fruit, non-starchy vegetables, and whole grains is associated with positive outcomes regarding CRC development. The aim of the present study was to evaluate the dietary intake of plant-based food and food groups, along with lifestyle habits of CRC patients. A case-control study was conducted during April 2015 – October 2017. Patients (n=151) recently diagnosed with CRC and undergoing conventional treatment were recruited from Medisprof Oncology Hospital. Controls (n=151) were selected randomly from generally healthy adults. Dietary and lifestyle data were collected during a face to face interview and the applied lifestyle questionnaire included 74 items. The results showed that intake of specific food groups with high content of bioactive components was significantly higher in the control group compared to the CRC group (p<0.05), even though overall vegetable intake was similar between groups (p=0.51). Results also showed significant lower intakes of fiber-rich foods such as whole grains, nuts and legumes in the CRC group

Impacts of Non-Uniform Border Temperature Variations on Time-Dependent Nanofluid Free Convection within a Trapezium: Buongiorno’s Nanofluid Model

The present study develops the influence of inclined border temperature variations on the isotherms, streamlines, and isoconcentrations for unsteady free convection in a trapezoidal region filled with the water-based nanofluid. The considered mathematical nanofluid approach was formulated based on the Buongiorno&rsquo;s model. The set of governing partial differential equations formulated using non-dimensional primitive variables such as velocity, pressure, temperature, and nanoparticles concentration volume fraction was solved numerically using the finite element method for various magnitudes of control characteristics. It was revealed that control characteristics affected the liquid circulation and energy transport coefficients. The Nusselt number is a growing function of wave number, amplitude, and the Rayleigh number

Blasius Problem with Generalized Surface Slip Velocity

This paper considers the classical problem of the steady boundary layer flow past a semi-infinite flat plate first considered by Blasius in 1908 with generalized surface slip velocity. Numerical solutions are obtained by solving the nonlinear similarity equation using the bvp4c function from MATLAB for several values of the slip parameters

Impacts of Non-Uniform Border Temperature Variations on Time-Dependent Nanofluid Free Convection within a Trapezium: Buongiorno’s Nanofluid Model

The present study develops the influence of inclined border temperature variations on the isotherms, streamlines, and isoconcentrations for unsteady free convection in a trapezoidal region filled with the water-based nanofluid. The considered mathematical nanofluid approach was formulated based on the Buongiorno&#8217;s model. The set of governing partial differential equations formulated using non-dimensional primitive variables such as velocity, pressure, temperature, and nanoparticles concentration volume fraction was solved numerically using the finite element method for various magnitudes of control characteristics. It was revealed that control characteristics affected the liquid circulation and energy transport coefficients. The Nusselt number is a growing function of wave number, amplitude, and the Rayleigh number