New Approaches to Thermal Protection Wetsuits Development for

Long-distance Swimmers Competing in Open Water

Alexander Bolotin and Vladislav Bakayev

Institute of Physical Education, Sports and Tourism, Peter the Great St. Petersburg Polytechnic University,

29, Polytechnicheskaya Str, St. Petersburg, Russia

Keywords: Wetsuits, Mathematical Model, Long-distance Swimmers, Thermal Characteristics, Thermal Exchange,

Open Water Swimming Competitions, Thermal Manikins.

Abstract: The article provides analysis of modern views on the development of thermal protection wetsuits for

swimmers competing in open water. Requirements to generation of the predictive model of wetsuits are

assessed in order to determine thermal characteristics of materials to be used to manufacture these wetsuits.

Requirements to the simulating model are provided according to modern methods of assessment of thermal

properties of material and physiology of athletes competing in open water. It is determined that due to many

structural designs, features, thermogenesis dynamics and other devices’ indices, the most promising method

of experimental assessment of wetsuit materials’ thermal characteristics is a use of thermal manikins. The

article provides classification of modern thermal manikins and their parameters for manufacture of wetsuits.

1 INTRODUCTION

Development of promising, more ergonomic

prototypes of wetsuits for marathon swimmers and

their practical significance at the current stage of

sport development consist in objective necessity for

arranging of more comfortable conditions for their

training and competitive activity. Objective

necessity for improvement of existing wetsuits for

swimmers who compete in open water is also related

to the necessity for development of corresponding

materials in order to improve competitive result and

thermal characteristics. Currently, within the wetsuit

quality indicator system, hygienic indicators are the

most significant, they determine swimmer body

thermal status, depend on heat and gas exchange

between the body “envelope” and environment that

is the entity of thermal regulation during training

and competitions. Artificial microclimate should be

created between athlete’s body and wetsuit

envelope; it provides comfortable conditions for

vital activity of a swimmer, with minimum stress of

thermal regulation function.

The recent studies show that application of

modern wetsuit thermal characteristic assessment

methods ensures the most accurate selection of

materials for wetsuit manufacture (Abramov and

Rodicheva, 2009, Abramov and Rodicheva, 2012,

Bohuslavska et al., 2017). With that, application of

thermal manikins enables to avoid involvement of

volunteer testers for physiological and hygienic

assessment of the sportwear sets to be created, thus

significantly reducing financial expenses and

excluding subjective factors.

2 ORGANIZATION AND

METHODS

The main study method is predictive simulation

modelling carried out according to modern methods

of assessment of material thermal properties and

physiology of athletes competing in open water.

Analysis includes current methods of material

thermal characteristics assessment for manufacture

of sportwear.

Current approaches to selection of materials for

wetsuits enable to predict thermal exchange process

in the “swimmer – wear – water medium” system,

using mathematical models (Abramov and

Rodicheva, 2012, Bakayev and Bolotin, 2017,

Bolotin and Bakayev, 2017a, Bolotin and Bakayev,

2017b). The purpose of mathematical prediction of

“swimmer – wear – water medium” system

Bolotin, A. and Bakayev, V.

New Approaches to Thermal Protection Wetsuits Development for Long-distance Swimmers Competing in Open Water.

DOI: 10.5220/0010136402230227

In Proceedings of the 8th International Conference on Sport Sciences Research and Technology Support (icSPORTS 2020), pages 223-227

ISBN: 978-989-758-481-7

223

condition is development of the thermal regime

mathematical model for this system taking into

account all existing factors of water medium,

competitive activity specific features of athletes

competing in open water, their physiology and heat-

regulating structures principles (Bolotin and

Bakayev, 2020, Gayvoronskiy et al., 2014,

Zakharova and Mekhdieva, 2016). We have

developed generalized algorithm that is used when

building these mathematical models:

1st stage: preparation of the predictive model

design geometry.

2nd stage: description of thermal exchange

processes of swimmers within the fragment and on

its boundaries. Calculations can be carried out using

thermodynamic relations or in differential form.

3rd stage: setting of physical, initial and

boundary conditions of the model that consider

process features conditioned by interaction between

materials and athlete’s body and water medium.

4th stage: numerical solution of equations taking

into account physical, initial and boundary

conditions.

5th stage: visualization the results of basic

solution complex for the predictive model.

3 RESULTS

Calculation results are represented as specific

temperature distributions in materials or as

temperature or heat flow field distribution. When

carrying out further calculations or assessment of

swimmer thermal state, average values can be used.

Field distribution shows dynamics of the processes

under consideration and, to a better degree, enables

to determine influence of the considered material set

option on thermal exchange processes within the

“swimmer – wear – water medium” system.

Generalizing modelling features at each of specified

stages, the whole range of thermal exchange

mathematical models is subdivided into the

following models:

1. Predictive models for calculating thermal

exchange within the “swimmer – wear – water

medium” system under conditions of steady-state

thermal exchange. In order to describe thermal

exchange in materials and their boundaries these

models apply thermodynamic relations.

2. Mathematical simulation models to calculate

thermal exchange within the “swimmer – wear –

water medium” system under conditions of dynamic

thermal exchange. In order to describe a thermal

exchange in multi material stacks and at their

boundaries these models apply differential

equations. This enables to consider thermal

properties of materials for wetsuits and water

medium parameters when carrying out calculations.

Predictive models that apply thermodynamic

relations are mainly applicable to calculation of

thermal exchange in stacks of traditionally used

materials. As design geometry in these models,

vertical section of material package is used that was

initially proposed by Kolesnikov P. A. (1971) for

rectangular and cylindrical geometry (Figure 1).

Figure 1: Design geometry of the classical predictive

model of thermal exchange in the material stacks.

Thermal exchange processes in these options of

the design geometry are described using original

interpretations of classical Fourier, Stefan –

Boltzmann, Newton – Richmann thermal exchange

laws. The main disadvantages of predictive models

for calculation of thermal exchange within the

“swimmer – wear – water medium” system under

conditions of steady-state thermal exchange are:

1. Computation is carried out with constant

values of thermal properties of materials that does

not enable to consider dynamics of improved

properties of the modern materials.

2. The model considers water temperature and

water current velocity. At the same time, objective

data of the thermodynamic relations provided are not

considered.

Thus, predictive models within the “swimmer –

wear – water medium” under steady-state thermal

exchange can be used to calculate thermal exchange

between an athlete and water medium under

moderate and severe cold conditions, when variation

of conditions in the “swimmer – wear – water

medium”, can be conditionally considered as

neglectable. Methods of simulation mathematical

modeling, that use differential equations enable to

carry out multiple computations under various initial

conditions that provides the possibility of more

Internal

stack surface

External

stack surface

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detailed modeling of operational efficiency of

wetsuit thermal properties at dynamic conditions of

thermal exchange.

Application of these methods provides wide

range of mathematical models of thermal exchange

in material package. For example, computer model

“Computational Bioengineering System for Thermal

Functional Design of Textile Products” enables to

carry out calculations taking into account wide range

of factors (

Lijing, 2008)

. Introduction of input

parameters for each subsystem of the “swimmer –

wear – water medium” integrated system provides

qualitatively efficient interface form. The list of

environment parameters is provided for the

following factors: water temperature, current water

velocity. The program enables to set wide range of

physiological parameters of athlete’s organism that

determine his/her level of thermogenesis. Physical

properties of materials are set as functions and tables

that enables to better consider dynamics of new

material improved properties in case of variation of

thermal exchange conditions within the “swimmer –

wear – water medium” system. Predictive simulation

models of thermal exchange in the material package

are combined with mathematical models of thermal

exchange of a swimmer that enable to present body

morphology and influence of organism thermal

regulation mechanisms in order to obtain more

accurate results.

Currently, attempts to describe thermal exchange

processes within the “swimmer – wear – water

medium” system are made taking into account

athlete's body morphological traits or its individual

elements.

“Human thermal comfort model”, proposed by

the specialists of National Renewable Energy

Laboratory is one of the most elaborated

mathematical models of human body thermal

exchange taking into account thermal regulation

mechanisms (Farrington et al., 2004). Its geometry is

three-dimensional and assumes exact representation

of morphology of each human body layer. Model

representation of a leg in the area of human thigh is

shown in Figure 2.

This model considers all body features accurately

enough, that is achieved by using of about 40,000

nodes in the calculation. When carrying out

calculations, material stack of the sportwear set

under consideration can be represented fully enough.

It is reasonable to define materials thermal

conductivity value using one of the methods of the

below-stated classification of experimental studies

of their thermal properties.

1. By the type of the thermal exchange condition

to be modeled within the “swimmer – wear – water

medium” system:

- Methods based on the steady-state condition

principles.

- Methods based on the dynamic condition

principle, that, in turns, are subdivided into

unsteady-state and quasi steady state conditions.

2. By configuration of the sensing element:

- Methods that use a flat sensing element.

- Methods that use a cylindrical sensing element.

- Methods that use spherical sensing element.

- Methods that use a sensing element that is very

similar to swimmer body morphology in terms of

configuration.

The last group of methods includes application

of thermal manikins that are characterized by wide

variety of structural design, structural features,

thermogenesis dynamics and other indicators.

Therefore, there was a proposition on the

following generalized classification of modern

thermal manikins:

1. By quality of temperature field representation

on a surface, low-segment and multi-segment

thermal manikins are distinguished.

2. By type of processes to be modeled general

and “perspirable” thermal manikins are distinguished.

3. By parameters of dynamics static,

“swimming” and “breathing” thermal manikins are

distinguished.

a) b) c) d) e)

Figure 2: Model representation of a human body as a system of nested cylindrical envelopes in the human thermal exchange

model of NREL (а – model representation of a leg in the area of a thigh; b – bone tissue model representation; c – muscle

layer model representation; d – subcutaneous tissue layer model representation; e – skin model representation).

New Approaches to Thermal Protection Wetsuits Development for Long-distance Swimmers Competing in Open Water

225

Thermal manikin is a thermal model of a human

body where the following is represented accurately

enough:

- human body organization morphological

features;

- features of heat generation processes within the

volume of a thermal manikin taking into account

variable intensity of the work to be performed;

- features of the process of heat dissipation from

a body surface.

There are two main components required to be

distinguished in the thermal manikin structure:

external envelope and automation system located

inside (Figure 3). The thermal manikin envelope

consists of individual segments each of which is an

independent and finished node that differs from

other segments by external shape. The segment of

modern thermal manikins is equipped with a heater,

temperature gauge and heat meter connected with

the automated system. Heater operation mode is

controlled by the automated system on the basis of

difference between temperature gauge readings and

the target temperature value set in the program. A

heat meter enables to measure amount of heat

consumed to maintain the set temperature. The

segment of “perspirable” thermal manikins is

equipped with the nozzles that supply fluid

simulating body perspiration.

The thermal manikin automation system is

equipped with software packages that regulate

heating and nozzle operation modes for each

segment depending on its location. Segments can

have various sizes and configuration that enables to

approximate temperature field on a thermal manikin

surface to distribution that is specific to a human

body.

Low-segment thermal manikins contain about

10–15 segments. Their shape conditionally conforms

to human body morphology. Multi-segment thermal

manikins contain about 30 segments. The most

accurate representation of human body morphology

is ensured in ADAM thermal manikin design due to

application of 150 segments (Mandal et al., 2017).

Using the software package “Human thermal

comfort model” developed by the socialists of the

University of California, Berkeley (Farrington et al.,

2004), sufficiently high degree of similarity of

temperature distribution on a thermal manikin

surface to distribution observed on a human body

surface is ensured.

“Breathing” and “swimming” dynamic thermal

manikins enable to study influence of swimmer

dynamics during wetsuit operation on his/her

thermal state. One of the most commonly used

“breathing” thermal manikins is engineered by T. L.

Madsen (1999). Likewise human body, a thermal

manikin breathes colder ambient air in and breathes

Figure 3: Thermal manikin diagram.

Human body regulator that

controls data

transmissions and

regulates main body

functions

Ambient air

humidity

breathing

system

Internal wate

tank

Evaporation

transmission

system

Wireless data transmission:

Model surface temperature

Heat flux and sweat rate regulato

for a manikin

Wireless

receiver

Single manikin area (150

typical area on a body)

Surface segment +

controller

Surface segment

controller

Storage battery (24

V). (At least, two

hours of manikin

operation)

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warmer air out. Respiration rate is regulated by

means of the program.

Application of thermal manikins enables to study

processes that occur in the material package of

wetsuit thermal properties in more detail.

Particularly, using them the following can be

measured: temperature field distribution on a

thermal manikin surface and in wetsuit structure,

heat flux density on a thermal manikin surface.

4 CONCLUSIONS

Due to the necessity to improve sportwear, a

question of quality of materials to be used can be

solved using various assessment methods and the

respective software that can process formulas of

classical thermal exchange laws. Study methods

using thermal manikins are very similar to

experimental methods involving testers. When

carrying out studies on development of new wetsuit

prototypes it is necessary to involve specialists in the

field of exercise physiology, human thermal

exchange, programming, sports metrology.

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