Understanding how a Heater in a Room affects our comfort is something we all experience in daily life, which makes this CFD simulation both practical and fascinating. When we turn on a heater, invisible but powerful natural convection currents begin moving warmed air throughout the space, creating complex patterns that directly impact our thermal comfort. Using ANSYS Fluent, we’ve built a detailed model that predicts exactly how heat spreads from a simple heater to all corners of an enclosed room. The simulation captures essential physics including buoyancy-driven flow, temperature distribution, and even surface-to-surface radiation (S2S) that accounts for heat moving directly between solid surfaces without heating the air in between. This type of building environment simulation helps engineers design more efficient heating systems and optimize indoor climate conditions without costly trial-and-error with physical prototypes.

Figure 1: Heating the room with heater CFD Simulation

Simulation Process

It has tried to use the simplest model, focusing on the performance of a heater and its roll in ventilation. Indeed, our model is established from two zones. One is the solid heater and the other is the air zone. The structured grid rockets the accuracy of the present study. A source term applies the heat generation in 100 W/m3 in the heater zone. The Surface-to-surface (S2S) radiation model considers the radiative effects, so the volume impacts are not included.

Figure 2: structured grid over the model

Post-processing

Looking at the velocity contour, we can see how the heater in a room creates a distinct pattern of moving air. The fastest air movement (red area, around 0.124 m/s) happens right above the heater as warm air rushes upward due to buoyancy forces. This creates what engineers call a thermal plume – basically a column of rising hot air. Most of the room stays pretty calm with speeds below 0.03 m/s (dark blue regions), which is why you can’t really feel air movement when sitting away from a heater. The streamline visualization tells an even more interesting story, showing how air actually travels in the room. Notice the swirling patterns and multiple recirculation zones throughout the space. These circular motions happen because warm air rises to the ceiling, cools down a bit, then falls back toward the floor, creating a continuous natural convection loop. This is exactly why rooms heated by a single heater often have cold spots – the air doesn’t move evenly everywhere.

Figure 3: Buoyancy-driven flow due to heater and natural convection in a room

The temperature distribution shown in the 3D view reveals how heat spreads through the room. The heater itself appears as a small rectangular object with the highest temperature (around 301.5K or 28.5°C), while most of the room stays closer to 300K (27°C) – that’s only a 1.5°C difference! This small temperature range might surprise you, but it shows how thermal radiation and slow air movement gradually even out temperatures throughout the space. You can also spot the faint blue regions where slightly cooler air sinks back down after losing heat to the walls. This pattern of thermal stratification – where warmer air collects near the ceiling and cooler air stays lower – is why many people install ceiling fans to push this warm air back down in winter. The simulation perfectly captures the physics of indoor climate and helps explain why you might feel chilly even when the average room temperature seems adequate on a thermostat.

Figure 4: Temperature field around the heater in the room