This article explores the critical role of physical models in simulating degradation effects in GaN nanowire field-effect transistors (NW-FETs). With the rapid advancement of nanoscale device technology, accurate prediction of electrical and radio-frequency (RF) characteristics under stress conditions requires advanced physical modeling. Phenomena such as hot-carrier injection, self-heating, trap dynamics, and polarization effects strongly influence device reliability and performance. By analyzing these mechanisms within Sentaurus TCAD, the study demonstrates how proper selection and calibration of physical models enable simulations to closely correspond to experimental results. The findings highlight that neglecting key models can lead to significant errors in predicting gate/drain lag, current collapse, and long-term reliability, underlining the necessity of precise model choice for both academic research and industrial applications.