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Due to the fact that modern technologies are getting smaller and more compact and are anticipated to perform better, there has been an increase in interest in heat transfer enhancement employing hybrid nanofluids in tubes and channels in recent years. This study seeks to establish an outward saw tooth corrugated wall model-based predictive friction characteristic for internal tube flow. Computational Fluid Dynamics (CFD) was used to simulate the model numerically. The response behaviour study was then conducted utilising the Design of Experiment (DOE) and the Response Surface Methodology (RSM). The established surrogate model has led to the consideration of RSM. In this study, the DOE was executed by utilising the Box-Behnken Design (BBD) method with two-level factorial by considering three parametric factors which are: (a) 10000 to 30000 axial Reynolds number, Re, (b) 1mm to 4mm wave amplitude, a, and (c) 5mm to 20mm wavelength, lw. The results showed that the expected response surface values are consistent with the CFD values and that the predictive model is therefore reliable. The R-squared (R2) value is 98.25%, indicating that the model can predict new observations. The wavelength and wave amplitude show significant factors influencing the friction factor which is -0.11235 and 0.14861 respectively and this is based on the normal plot of the effect from the regression model from RSM. These results provide data for estimating the geometric characteristics of tube corrugated wall.

In recent years, there has been an increasing interest in heat transfer enhancement using nanofluids in channels due to current devices become smaller and more compact and are expected to perform better. Thus, we attempt to introduce hybrid nanofluids flow in a straight pipe using Ansys Fluent software. The simulation was prepared with certain specific parameters such as the hydraulic diameter is set at 10mm, the flow is a continuum, the Reynold number in the range of 5000 to 30000, k-e turbulent model used in this simulation, the inlet temperature 297 K, and the uniform temperature along the pipe at 313 K. This study was carried out on Al2O3+Cu / water hybrid nanofluids to analyse the thermal improvement and friction factor of nanofluids occur in a straight pipe. Then, the numerical results obtained were compared between mono and hybrid nanofluids. It was found that the mono nanofluids at 1% and 4% indicate a significant increase in Nusselt number at 17% and 24% respectively and hybrid nanofluid increase at 2% to 5.6% compared to base fluid. Whereas the friction factor remains similar for all the nanofluids. However, the performance evaluation criterion (PEC) has shown that hybrid nanofluids remain lower than mono nanofluids.

A new meshless-based solver has been used to study the deformation of flexible structure due to water dam break. This meshless Fluid Structural Interaction (FSI) solver couples the Smoothed Particle Hydrodynamics (SPH) and Lattice-Spring Model (LSM). SPH and LSM are used to model the motions of fluid and solid particles, respectively. As both are essentially particle-based methods, the force coupling at the interface is straightforward. The numerical results have been compared with the benchmark numerical solutions of dam break problem and good agreement has been found.

Ventilation shaft is one of the effective elements in natural ventilation for ensuring acceptable Indoor Air Quality (IAQ) and thermal comfort. It has been found that the opening of ventilation shaft plays a significant role in the ventilation efficiency of an underground shelter. In this study, we aim to develop a predictive ventilation rate model for a naturally-ventilated underground shelter. Computational Fluid Dynamics (CFD) was employed as a simulation tool, where the result was validated with experimental data obtained from the previous literature. Goal Driven Optimization (GDO) was used for the optimization process by considering three geometrical factors and their effects on the objective function. From this study, it is found that the predicted response surface values agree well with the CFD values and hence the predictive model is reliable.

Pulsating Heat Pipe (PHP) is the next generation heat pipe that has a prospect in improving the heat transfer performance. The type of working fluid use in the PHP has a direct influence on the thermal performance. Incorporating nanofluid in PHP may greatly increase its thermal performance as compared to using base fluid (water). The current work focuses on the simulations of 2-dimensional flows in PHP using working fluids such as diamond, silver (Ag), silica oxide (SiO2) nanofluids and water. Constant heat flux and filling ratio of 50% were used throughout the study. From the results, it was found out that diamond nanofluid has the lowest thermal resistance value as compared to other working fluids. The effect of the number of PHP turns was studied and it was discovered that higher number of turns would produce lower thermal resistance value.

In this study, the soil temperature profile was computed based on the harmonic heat transfer equations at various depths. The meteorological data ranging from January, 1st 2016 to December, 31st 2016 measured by local weather stations were employed. The findings indicted that as the soil depth increases, the temperature changes are negligible and the soil temperature is nearly equal to the mean annual air temperature. Likewise, the results have been compared with those reported by other researchers. Overall, the predicted soil temperature can be readily adopted in various engineering applications in Malaysia.