# A Validated Thermal Computational Fluid Dynamics Model of Wine Warming in a Glass
###### Abstract  
Oenophiles are aware that the temperature at the time of drinking can profoundly shape wine's sensory attributes. Wine is usually served and drunk below room temperature but warms up after pouring due to heat exchange with warmer surroundings. This study investigates how quickly wine warms up in a wine glass and identifies the relevant heating effects. A numerical simulation using conjugate heat transfer is established, representing the complex multi-physical process. Experiments are conducted to validate the simulation. It is shown that the simulation must take into account thermal conduction, convection, and even radiation to provide accurate results. Without simulating radiation and convection of the room air, the predicted temperature is off by 66.3% or 3.3 degC. As warming is independent of the alcohol content, the simulation results are valid for non-sparkling wine types with moderate sugar levels within the considered configuration. A parameter study investigated the temperature increase over time depending on the ambient temperature and the initial wine temperature for 150 mL wine in a medium-sized red wine glass. The results can provide information on preparing a wine to obtain the desired drinking temperature. wine; glass; conjugate heat transfer; simulation; CFD; thermal radiation +
Footnote †: journal: _Sci._  
Several studies showed the influence of the drinking temperature on the sensory attributes of wine. Cool temperatures decrease the human perception of sweetness and increase the perception of sourness [14]. Bitterness and astringency get more pronounced with decreasing wine temperature [14; 15]. Higher wine temperatures increase volatility, allowing more compounds to dissolve from the wine in the glass and enhance the wine's aroma [1; 15; 16]. The panelists in a study by [PERSON] et al. [16] perceived red wines at 16 \({}^{\circ}\)C rather as bitter and astringent and less sweet compared to the same wines tasted at 22 \({}^{\circ}\)C. The red wines were more often described with aromatic attributes at 16 \({}^{\circ}\)C than at 10 \({}^{\circ}\)C. According to [2; 17], wine can smell and taste too alcoholic when it is too warm due to the accelerated evaporation of ethanol. Although the drinking temperature preference may be individual, there are general guidelines for the serving temperature of the different wine types. The Oxford companion on wine by [PERSON] and [PERSON] [2] specifies that full or tann red wines should be served at 15 \({}^{\circ}\)C to 18 \({}^{\circ}\)C. In contrast, medium-bodied and light red wines are usually offered a few degrees colder. Full and complex dry white wines should be served at 12 \({}^{\circ}\)C to 16 \({}^{\circ}\)C. Dry (aromatic) white wines with a medium or light body are liked most at around 8 \({}^{\circ}\)C to 12 \({}^{\circ}\)C serving temperature. Sweet, light white wines should be offered even cooler at around 5 \({}^{\circ}\)C to 10 \({}^{\circ}\)C. It is recommended that the wine should usually be served at the lower end of the indicated ranges since it warms up relatively fast in the glass [2]. To the best of the authors' knowledge, no profound information is available on how fast wine warms up in a glass. This study aims to close this gap and examines the physical process of wine warming in a glass and determines the wine's temperature change over time. The warming process is modeled and computed using numerical simulation. The simulation can reveal the governing heating phenomena and can be easily applied to different configurations for similar heating problems. A conjugate heat transfer simulation models the crucial heating mechanisms such as thermal conduction, convection, and radiation. The simulation approach considers only non-sparkling wines. Buoyancy effects due to rising bubbles are not included. Sweet dessert wines or fortified wines with high sugar content are not examined either.