Penalty finite-element analysis of coupled fluid flow and heat transfer for in-line bundle of cylinders in cross flow
Abstract The two-dimensional steady state Navier-Stokes equations and the energy equation governing laminar incompressible flow are solved using a penalty finite-element model for the case of flow across an in-line bundle of cylinders. Two cases of in-line cylinder bundles, one five rows deep and the other an infinite bundle, are considered with pitch-diameter ratios of 1.25, 1.5 and 1.8 Reynolds numbers studied range from 100 to 600 and Prandtl number is taken as 0.7. Velocity field vectors, stream lines, vorticity, pressure and temperature contours, local and average Nusselt numbers, pressure and shear stress distribution around the cylinder walls and drag coefficients are presented. The results obtained agree well with available experimental and numerical data.
A real case of a steel lattice shell suffering a fire was studied. Based on the theory of field modeling, fire dynamic simulator (FDS) was used to identify the temperature field. The damage mechanism of the structure was determined by FEM analysis. After damage assessment, the shell was repaired with the pipe-encasement method. Finally, field test was employed to check the capacity of the structure after repair. The numerical study results indicate that the damage assessment agrees well with field inspection, verifying the accuracy of fire numerical simulation and FEM analysis. The field test results prove that the pipe-encasement method is secure and reasonable, and the repaired shell is safe.