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Thermal manikin general information

• Thermal Neutrality
• Comfort Models
• Comfort Assessment
• Local Comfort

For detailed technical information see: Theory Manual

For over 60 years now, manikins have been used to study the thermal interaction between people and their environments. US-Army researchers have used thermal manikins to measure thermal and water vapor resistance values of clothing since the 1940s to help improve functional performance and thermal comfort. Through the years the sophistication of these manikins has improved and can now mimic sweating and breathing.

Under the name 'manikin', one thinks of a dummy in which the skin temperature is controlled by digital or analog means and sweating is produced through valves and hoses that pump water through dozens of holes on the dummy. However, the integrated thermal Manikin within THESEUS-FE, called FIALA-FE, is not in the sense of the word a physical manikin, but rather a simulated one. The thermal relationships are described by equations, functions and appropriate parameters. The sophistication of FIALA-FE greatly surpasses the capabilities of modern physical manikins. Life-like simulations can be performed by taking into account such aspects as blood flow, breathing, evaporation, metabolic responses, sweating, shiver, cardiac output and a complete energy balance between the manikin and its environment.

	L [cm]	Sector	φ [deg]	Material	Radius r [cm]	Conduct k [W/m/K]	Density ρ [kg/m3]	Spec. Heat c [J/kg/K]	Blood perfus. wbl,0 [ltr/s/m3]	Metbol. qm,0 [W/m3]
Head (sphere)		Forehead Head	10 170	Brain Bone Fat Skin	8.6 10.05 10.20 10.40	0.49 1.16 0.16 0.47	1,080 1,500 850 1,085	3,850 1,591 2,300 3,680	10.132 0 0.0036 5.48	13,400 0 58 368
Face (cylinder)	9.84		210	Muscle Bone Muscle Fat Skin	2.68 5.42 6.80 7.60 7.80	0.42 1.16 0.42 0.16 0.47	1,085 1,500 1,085 850 1,085	3,768 1,591 3,768 2,300 3,680	0.538 0 0.538 0.0036 11.17	684 0 684 58 368
Arms (cylinder)	63.7	Anterior Posterior Inferior	135 135 90	Bone Muscle Fat Skin	1.53 3.43 4.01 4.18	0.75 0.42 0.16 0.47	1,357 1,085 850 1,085	1,700 3,768 2,300 3,680	0 0.538 0.0036 1.1	0 684 58 368
...	...	...	...	...	...	...	...	...	...	...

At the center of the mathematical model for FIALA-FE is the Bioheat-Equation, see Fig. 1. This is a differential equation that balances the internal energy of the passive system through heat transfer and heat storage, in other words metabolism and blood flow. Mathematically, the human organism is separated into two interacting systems: the controlling active system, see Fig. 2 and the controlled passive system. FIALA-FE combines both, passive and active systems, in a complex model that reaches a good fit with field measurements of human thermal responses in a wide range of environmental conditions.

FIALA-FE combines both passive and active system in a complex model that reaches a good fit with experimental results. Blood flow through the arteries transports heat and causes a warming of the body. In cold environments the blood vessels contract (vasoconstriction), causing blood flow to be restricted or slowed, retaining body heat and increasing vascular resistance, thus causing less heat to reach the skin surface. In warmer environments blood vessels widen (vasodilatation). The flow of blood is increased due to a decrease in vascular resistance and more heat reaches the surface of the skin.

The complete mathematical/physical model is mainly based on the internationally recognized work from D. Fiala. In his research, special attention was given to life-like modeling thermal reactions of each body part and he suceeded in producing an improved modeling technique for not only global but also local skin temperature. In his effective validations D.Fiala collected comprehensive test data from literature and compared measured skin temperatures with simulated manikin results, see Fig. 3. The correct modeling technique of our manikin (FIALA-FE) could be demonstrated in a special manual that shows good fitting of simulated results and test data.

In THESUS-FE two different representations of the Manikin exist: one is an internal representation that the solver uses, and the other is the GUI representation for the user, see Fig. 4. Internally, the manikin is represented as 15 different body elements, each body element differing in material based on the skin, fat and muscle structure of the specific part, see Fig. 5. This internal discretization uses special finite elements that, like layers of an onion, build up the solid model. In the GUI however, the user works with a corpse represented by standard shell elements. Boundary conditions and clothing can be uniquely applied to different regions of the body. Then in the post-processing, the calculated temperature of the skin and clothing are plotted on the shell elements, see Fig. 4.

Different types of boundary conditions can be applied to the manikin: convection, evaporation, breathing and even contact, see Fig. 6. Once boundary conditions are applied, short-wave radiation from the sun as well as long-wave radiation between finite elements is taken into account. Environmental parameters that typically affect the thermal state of the manikin are...

• adjacent air temperature and humidity
• relative air speed
• radiation wall temperature(s)
• radiation view factors
• contact relations (e.g. with the seat)

THESUS-FE supports fully-coupled heat and mass transfer, see Fig. 7, between airzones and structure elements. This feature is especially applicable to the coupling of the manikin FIALA-FE with its environmental air. To demonstrate this we imagine the interior of an automobile cabin. This airzone is represented by two degrees of freedom, temperature and humidity. The boundary conditions for this airzone are called ventilations and constitute mass flow at a given temperature (e.g. air conditioning/ventilation systems). The manikin is a source of heat and moisture through breathing and evaporation which is then transferred to the cabin environment. Therefore, in an unventilated car with occupants, the humidity level will rise.