## 5 Materials and Methods
### Thermophysical Characteristics of the Simulated Breast Model  
The heat transfer system is depicted in Figure 1, Equation (1), and their associated boundary conditions were solved by utilizing COMSOL Multiphysics 5.3 software. Moreover, the sizes and properties of the tissue are listed in Table 1. COMSOL's bioheat transfer system was used to simulate thermophysical properties and boundary conditions. Extra fine mesh size was used because it was appropriate for breast tissues with a high density of the breast. A previous study proposed estimating breast tumors from surface-level temperature changes by relying on theoretical calculations that employ some form of the optimization process to identify tumor characteristic features such as depth, size, heat generation, thermal conductivity, and blood perfusion. However, such features were typically estimated based on a variety of other thermal conductivities of cancer and healthy tissue. In Figure 2, the hemispherical 3D breast model is represented numerically by a mesh. Breast tissue is composed of multiple layers. The thermal model of the breast was analyzed in various scenarios in this project. The surface temperature on the breast skin was reviewed first, followed by the change in temperature between tumor cells and healthy breasts. Finally, the normalized temperature changes were evaluated. In the literature reviews, most of the studies suggest tumors in the breast from surface temperatures, which are based on numerical simulation using some optimization methods. All of the following are required in order to identify the characteristics of tumors: depth, size, heat generation, thermal conductivity, and blood perfusion. This study examines the breast's characteristics under various conditions. This study first examines the thermal form of the skin of the breast. It then compares the breast thermal images with cancer and without cancer. Finally, it evaluates the standard thermal changes by separating each temperature by its specific high rate. This study carries out the following analysis steps: \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Tissue Layers** & **Thickness \(\sigma\) (cm)** & \
\begin{tabular}{c} **Thermal Conductivity,** \\ \(k\) **(W/mK)** \\ \end{tabular} & **Blood Perfusion, \(w\) (s\({}^{-1}\))** &
\begin{tabular}{c} **Heat Source, \(Q\)** \\ **(W/m\({}^{3}\))** \\ \end{tabular} \\ \hline Skin & 0.16 & 0.45 & 0.00018 & 368.1 \\ \hline Fat & 0.5 & 0.21 & 0.00022 & 400 \\ \hline Gland & 7 & 0.48 & 0.00054 & 700 \\ \hline Muscle & 2.3 & 0.48 & 0.0027 & 700 \\ \hline Tumor & 1 & 0.62 & 0.016 & 50,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Biological tissues layers of the breast [11; 26; 27; 28] used in COMSOL simulation model. It examines the changes in tumor location by analyzing thermal profiles on the breast surface for nine different scenarios in which the tumor is located at nine different depths, as depicted in Figure 3 as tumors T1-T9. 2. It examines the changes in tumor size by analyzing three various tumor sizes at the same geometric center, T3, and the diameter of tumor T3 was changed from 2 cm, 1 cm, and 0.5 cm with the same settings. 3. It examines the temperature production of a tumor (T3) by evaluating three various temperature generation rates: 29,500, 50,500, and 65,900 W/m\({}^{3}\). These values were chosen according to previous research on tumor temperature creation. 4. It investigates the blood flow in a tumor (T3) by analyzing three various values of blood flow rates: \(6.3\times 10^{-3}\), \(16\times 10^{-3}\), and \(50\times 10^{-3}\), per second. These rates were selected by taking the high and low rates from the average value reported in previous studies. 5. It analyses the thermal conductivity of T3 in the breast and looks at three different values, which are \(100\times 10^{-3}\), \(620\times 10^{-3}\), and \(1000\times 10^{-3}\), (W/mK). These rates were determined by taking the range of thermal conductivity values found in the literature and selecting high and low values. 6.