Background

With my first paycheck from a real job after grad school, I bought myself a Char-Griller Texas Trio Gas & Charcoal Grill with an offset fire box for smoking (it’s $700 now!?). That was almost 5 years ago and I haven’t gotten any better at maintaining a constant temperature when trying to offset smoke stuff. There are so many parameters to an offset smoker (inlet air, outlet air, fire positioning, total mass, etc.) that all the advice can get a bit overwhelming, especially when each smoke takes hours of time and loads of money (charcoal, wood, meat…). This is a quick project to see how the temperature of the space where the meat sits changes with all of these parameters changing. Will I actually use what I learn to improve my smoking? Probably not, the real answer is likely to buy a dedicated offset smoker but this seemed like a cheaper and faster way to at least try to gather some intuition on what’s going on.

The Physics Model

The simulation treats the smoker as a network of coupled thermal nodes:

• Firebox: A heat source with variable fuel input (wood + charcoal). The burn rate depends on oxygen supply, which is controlled by the intake vent.
• Cooking chamber: A horizontal cylinder with natural convection driven by temperature gradients. Heat transfers from the firebox via radiation and convection through the opening between chambers.
• Water basin: A thermal mass that absorbs and releases heat slowly. It also adds humidity, which affects how the meat surface temperature behaves.
• Cooking grate: The target node. This is where we want temperature stability.
• Steel body: The mass of the smoker itself acts as a thermal buffer and a heat sink to the environment.
• Ambient conditions: Wind speed, outside temperature, and humidity affect heat loss through the steel and through the exhaust.

Heat transfer between nodes uses:

• Conduction through the steel
• Natural convection driven by temperature differences
• Radiation between the firebox and chamber walls
• Advection from airflow through the system (intake vent -> firebox -> chamber -> exhaust)

Parameters

The key knobs I want to simulate:

Parameter	Effect
Intake vent area	Controls oxygen supply to the fire, hence burn rate and max temperature
Exhaust (chimney) height and diameter	Affects draft pressure and airflow rate through the system
Water basin volume and surface area	Thermal mass; more water means slower temperature swings but longer heat-up time
Fire size (initial fuel load and feed rate)	Baseline heat input
Barrel diameter and length	Total volume and surface area-to-volume ratio
Ambient wind	Dramatically affects heat loss through the steel
Meat mass and water content	Thermal load that changes over the cook as moisture evaporates

Implementation

The simulation uses a finite difference approach where each node has its temperature updated at each time step based on net heat flow. I’m writing it in Python with NumPy for the numerics and Matplotlib for visualization.

The goal is a tool where you can tweak any parameter and immediately see the temperature curve at the grate over a simulated cook. I want to answer questions like “does adding another gallon to the water pan actually help, or is it just more water to heat up?”

Code will be on GitHub once I have a working prototype.