Nusselt number (English spelling)

…In heat transfer, the amount of heat q passing through a unit area of ​​a wall per unit time divided by the temperature difference ⊿ T between the wall and the fluid is called the heat transfer coefficient, h = q /⊿ T , and the larger this value is, the better the heat transfer is. If the dimension representing the flow is L and the thermal conductivity of the fluid is λ, the dimensionless number defined as Nu = hL /λ is called the Nusselt number. According to dimensional analysis, in the case of forced convection, the Nusselt number is a function of the Prandtl number (which is also a dimensionless number and is defined as c _p μ/λ, where μ is the viscosity of the fluid and c _p is the specific heat at constant pressure) and the Reynolds number, and in the case of natural convection, it is a function of the Prandtl number and the Grashof number (defined as L ³ βg⊿ T /ν ² , where g is the acceleration of gravity, ν is the dynamic viscosity of the fluid, and β is the thermal expansion coefficient). …

*Some of the terminology explanations that mention "Nusselt number" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…熱伝達において，壁面の単位面積を単位時間に通過する熱量qを，壁面と流体の温度差⊿Tで割った値h＝q/⊿Tを熱伝達率と呼び，この値が大きいほど熱授受の良好さを示す。流れを代表する寸法をL，流体の熱伝導率をλとしたとき，Nu＝hL/λで定義される無次元数をヌッセルト数Nusselt numberと呼ぶ。次元解析によると，ヌッセルト数は，強制対流の場合，同じく無次元数であるプラントル数Prandtl number(流体の粘性率をμ，定圧比熱をc_pとして，c_pμ/λで定義される)とレーノルズ数の関数に，また自然対流の場合にはプラントル数とグラスホフ数Grashof number(重力加速度をg，流体の動粘性率をν，熱膨張率をβとしてL³βg⊿T/ν²で定義される)の関数になる。…

※「Nusselt number」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報