The model here is not a very good one in one important respect: opening the door twice in quick succession does not cost anywhere near twice as much as opening it once.
When you leave open the door, the colder air falls out the bottom and drags more warm air in past the contents, raising their temperature quite rapidly. While there is some additional turbulent mixing in the airflow around the initially moving door, it is not really significant compared with the overall downward convection flow inside the fridge. The flowing air cools and falls out the bottom continuously.
When you close it again, the airflow quickly reduces to almost nothing as the air stratifies by temperature—the coldest air is no longer free to flow out. The rate of heat transfer into the food reduces substantially. Eventually the air cools via the refrigerated walls and starts cooling the contents back to an equilibrium temperature, though this takes quite a few minutes.
So in terms of the important thing—temperature of the contents—you’re better off opening it each time as an open door heats the contents much faster than a closed one even with the same warm air in it.
The model here is not a very good one in one important respect: opening the door twice in quick succession does not cost anywhere near twice as much as opening it once.
When you leave open the door, the colder air falls out the bottom and drags more warm air in past the contents, raising their temperature quite rapidly. While there is some additional turbulent mixing in the airflow around the initially moving door, it is not really significant compared with the overall downward convection flow inside the fridge. The flowing air cools and falls out the bottom continuously.
When you close it again, the airflow quickly reduces to almost nothing as the air stratifies by temperature—the coldest air is no longer free to flow out. The rate of heat transfer into the food reduces substantially. Eventually the air cools via the refrigerated walls and starts cooling the contents back to an equilibrium temperature, though this takes quite a few minutes.
So in terms of the important thing—temperature of the contents—you’re better off opening it each time as an open door heats the contents much faster than a closed one even with the same warm air in it.