Hi use this below coding inbetween \makeatletter and \makeatother.
You can change any font for specific character, like v, w, y ...
For changing the font, Now i am using minion font, if you want times font use
ptm instead of pmn. Like that you can change to any font.
\documentclass{article}
\makeatletter
\DeclareSymbolFont{alphabets}{\encodingdefault}{pmn}{m}{it}
\SetSymbolFont{alphabets}{normal}{\encodingdefault}{pmn}{m}{it}
\SetSymbolFont{alphabets}{bold}{\encodingdefault}{pmn}{b}{it}
\DeclareMathSymbol{v}{\mathalpha}{alphabets}{"76}
\DeclareMathSymbol{w}{\mathalpha}{alphabets}{"77}
\DeclareMathSymbol{y}{\mathalpha}{alphabets}{"79}
\makeatother
\begin{document}
Stencils are an effective approach solving the wave equation in
the time domain. Memory bandwidth, not hardware threads, can
easily become the limiting resource if the stencil is parallelized
in the obvious way, because the arithmetic intensity will be low.
Caches ameliorate the problem somewhat, though greater gains can
be obtained by tiling. The problem is a stencil pattern in space
and recurrence pattern in time, so the tiles have a trapezoidal
shape in space--time. The slopes of the sides relate to the
stencil dimensions. Tiling recursively enables a cache-oblivious
algorithm, which optimizes for all possible levels and sizes of
cache while being oblivious to which really exist. Because the
resulting code uses cache more efficiently, it often runs faster,
even when run with a single thread, than the original serial code
runs. $v$ and $w$ and $y$.
\end{document}