A Heat Transfer in Gas Oil Tank CFD simulation is a computer model used to study temperature in large fuel tanks. This Thermal Management CFD is very important for the CFD for Petroleum Industry. The temperature inside a tank must be controlled to keep the fuel safe and maintain its quality. A Gas Oil Tank Fluent analysis helps engineers see how heat moves through the oil and the air above it. This is a complex Multiphase Flow CFD problem that includes both conduction and convection. Using this type of simulation helps engineers design better tanks with good insulation to reduce heat loss in storage tanks and prevent dangerous hot spots.

Figure 1: visual of  the Gas Oil Tank

Simulation Process: Fluent Setup, VOF Model for Transient Multiphase Heat Transfer

To perform this Oil storage tank heat transfer CFD study, we created a 3D geometry of the cylindrical storage tank in Design Modeler. We used the ANSYS Meshing tool to create a high-quality grid of cells throughout the tank’s volume. Because this problem involves two fluids, liquid oil and gas, we activated the Multiphase VOF (Volume of Fluid) model in ANSYS Fluent. This model is excellent for tracking the clear surface between the oil and the gas. Since the heating and cooling of a large tank happens over a long period, we correctly used a transient solver to capture these time-dependent changes. We applied convective heat transfer boundary conditions to the outside walls of the tank to simulate heat exchange with the surrounding environment.

Post-processing: CFD Analysis, Thermal Stratification and Buoyancy-Driven Flow

The temperature contour provides a clear map of the tank’s thermal state. From an engineering standpoint, this visual immediately confirms the presence of thermal stratification. The main body of the oil is at a high temperature, near 368.80 K (95.65°C), shown in red. The gas vapor space above it is much cooler, near 273.06 K (0°C), shown in blue. This distinct layering is a critical feature of large storage tanks and directly impacts fuel quality and vapor pressure. The simulation shows that heat is not evenly distributed but is layered by temperature.

Figure 2:  A temperature contour from the Transient Thermal Analysis, showing the thermal stratification within the oil and gas phases.

The temperature gradient and velocity contours explain why this stratification occurs and how the fluid behaves. The temperature gradient is highest at the tank walls and at the oil-gas surface, with values up to 289.26 K/m. These are the zones where heat is being actively transferred. This temperature difference causes the density of the oil to change. The warmer, less dense oil rises, and the cooler, denser oil sinks. This movement is called buoyancy-driven flow or natural convection. The velocity contour confirms this movement, showing slow but important circulation with speeds up to 0.046 m/s, mostly near the walls and surface. This gentle mixing is responsible for distributing heat throughout the tank. The most important achievement of this simulation is its ability to accurately model the complex interaction between heat transfer and fluid motion, proving that natural convection is the key mechanism driving thermal stratification in the tank and providing engineers with the data needed to predict heat loss and ensure stable storage conditions.

Figure 3: Professional visuals from the Natural Convection Simulation, showing a) temperature gradient and b) velocity contours, which highlight heat transfer zones and fluid motion.